[uk-ai-resilience] [uk-ai-governance] Tier C: Unpatched Critical CVEs in container images (libc6 CVE-2026-5450)

[github-actions]

Tier C — Restricted Pending Review

Source: UK AI Open Code Risk & Resilience Governance — 2026-07-27

Risk Scoring

Dimension	Score (1–5)	Notes
Exposure amplification	4	MCP server is runtime-facing; CVE in libc6 affects all process memory operations
Patchability	5	No upstream Debian fix available yet for CVE-2026-5450
Detectability	3	Memory-corruption exploits are moderately hard to detect
Operational fragility	3	Rebuilding images requires coordinated release
Ownership confidence	4	Named owners; active monitoring via container-image-scan workflow
Overall	3.8	High priority

Affected Images

• ghcr.io/github/github-mcp-server:v1.7.0 — CVE-2026-5450 (Critical), CVE-2026-5928 (High), CVE-2026-5435 (High) in libc6 2.36-9+deb12u14
• ghcr.io/github/gh-aw-node — similar libc6 issues

Remediation Action (SLA: High — 14 days)

1. Monitor [Debian Bookworm security tracker]((securitytracker.debian.org/redacted) for a libc6 patch
2. When a fix is published: rebuild and re-publish both images with updated libc6
3. Evaluate distroless or minimal base image to reduce libc6 attack surface long-term
4. Until patched: ensure MCP server network exposure is restricted to trusted callers

Exception (temporary, expires 2026-09-27)

• Threat hypothesis: Remote code execution via libc6 memory corruption
• Exploit acceleration: Moderate — public CVE, no PoC observed
• Operational weakness: Container rebuild blocked on upstream Debian patch
• Mitigation: Network isolation + weekly Debian tracker monitoring
• Expiry: 2026-09-27 — must be closed or renewed

Human Review Trigger

If CVE-2026-5450 PoC is published or CVSS is elevated to 9.0+, escalate to P0 rebuild immediately.

Related: #48151, #48150 | Governance discussion

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