Uncontrolled Memory Allocation in GNU cpio

Answer in brief

CVE-2026-66485 records a Medium severity (CVSS 4.6) vulnerability in Uncontrolled Memory Allocation in GNU cpio. The current sources do not mark it as known exploited. The current feed maps GNU/cpio (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 10, 2026Updated Aug 28, 2026Source checked Sep 24, 2026First seen by HOL Aug 10, 2026Material review Aug 28, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 4.6
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

CVSS is 4.6. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps GNU/cpio (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
GNU/cpiogeneric	0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for GNU/cpio.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 10, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 28, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 10, 2026

Sources and claim methodology

Upstream source description

GNU cpio is vulnerable to an uncontrolled memory allocation in the make_path function at src/makepath.c. The function uses alloca to allocate stack memory based on the length of argpath, which is derived from an archive-controlled pathname during extraction. A malicious cpio archive containing a sufficiently long nested pathname causes an unbounded stack allocation, resulting in a stack overflow and crash of the cpio process. An attacker who can supply a crafted cpio archive to a victim who extracts it can cause a denial of service. This issue has been fixed in commit 3cd514031371d8aeeaf2048aa10103e02831aaa9

Quoted source text, attributed separately from HOL analysis.