Windows ARM64: node_repl fails during sandbox runtime access validation with sharing violation after desktop update (26.1002.51308) #51633

Environment

• Windows 11 ARM64 running in a VM.
• Desktop version observed: 26.1002.51308, build 13417.
• Native Windows sandbox setting: elevated.
• The user reports that Computer Use worked before the update on October 7, 2026.
• Previous working version unknown. An update regression is suspected, not proven.

Minimal reproduction

1. Open a local task with node_repl available.

2. Execute only:

   nodeRepl.write('Laufzeit OK');

3. Reset the node_repl session once and repeat.

Expected: The text output succeeds without initializing Computer Use.

Actual: Both attempts fail before the requested JavaScript runs:

node_repl kernel exited unexpectedly
kernel_status: exited(code=1)
kernel_stderr_tail:
windows sandbox failed: helper_unknown_error: setup refresh had errors
reason: stdout_eof

Other attempts report:

trusted Node process exited unexpectedly; kernel reset, rerun your request

Specific sandbox evidence

Local username replaced with %LOCALAPPDATA%:

runtime read/execute validation failed:
validate runtime read/execute access on
%LOCALAPPDATA%\OpenAI\Codex\runtimes\cua_node\942963668be3d24b\bin\node_repl.exe:
open ACL target for root-only update:
Der Prozess kann nicht auf die Datei zugreifen,
da sie von einem anderen Prozess verwendet wird. (os error 32)

setup error: setup refresh had errors

Windows error 32 is a sharing violation.

An additional warning appears; its causal relationship is unknown:

failed to clean up stale arg0 temp dirs:
Zugriff verweigert (os error 5)

Isolation and recovery already tried

• The same minimal failure occurs in the original task and a fresh projectless local task.
• Session reset, full application restart, Windows restart, Windows app Repair and application reinstallation did not resolve it.
• Ending one identified additional cua-repl child process did not resolve it.
• Bundled node.exe successfully executes a plain console.log inside the normal workspace sandbox and reports arch=arm64.
• node_repl.exe opens successfully read-only with permissive sharing outside the sandbox.
• Its observed ACL grants the user full control and CodexSandboxUsers read/execute. This does not prove that sandbox access preparation is correct.
• No sandbox disabling, broad ACL changes, runtime-folder deletion or application Reset was performed.

Impact and request

Native Computer Use cannot start because its JavaScript runtime fails. Ordinary shell commands still work, distinguishing this case from reports where all shell execution fails.

Please investigate the Windows ARM64 node_repl runtime/sandbox access preparation and advise on a supported fix or an official previous-version package.

Similar symptom reports include #43255, #43373 and #51090, but an identical root cause has not been established.

Submitted by Codex at the affected user’s explicit request. No product source, test data, credentials, complete logs or session transcript are attached.