PatchSiren cyber security CVE debrief
CVE-2026-66485 GNU CVE debrief
GNU cpio is vulnerable to uncontrolled memory allocation in the make_path function at src/makepath.c, allowing a denial of service via crafted archive. The function uses alloca to allocate stack memory based on argpath length, derived from an archive-controlled pathname during extraction. A malicious cpio archive with a sufficiently long nested pathname causes unbounded stack allocation, resulting in a stack overflow and crash of the cpio process. Users and administrators should review their inventory, ensure patching, and monitor for potential exploitation attempts. This issue has been fixed in commit 3cd514031371d8aeeaf2048aa10103e02831aaa9. Evidence from official CVE record and NVD detail supports this assessment.
- Vendor
- GNU
- Product
- cpio
- CVSS
- MEDIUM 4.6
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-08-10
- Original CVE updated
- 2026-08-10
- Advisory published
- 2026-08-10
- Advisory updated
- 2026-08-10
Who should care
Users and administrators of GNU cpio, especially those who extract archives from untrusted sources, should be aware of this vulnerability and take steps to mitigate it. This includes reviewing their inventory of GNU cpio installations, ensuring they are patched, and monitoring for potential exploitation attempts.
Technical summary
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. This issue can lead to a denial of service.
Defensive priority
GNU cpio vulnerability allows denial of service via crafted archive; prioritize patching and inventory checks.
Recommended defensive actions
- Apply patch from commit 3cd514031371d8aeeaf2048aa10103e02831aaa9
- Inventory and verify GNU cpio installations
- Monitor for crafted cpio archives
- Restrict archive extraction to trusted sources
- Review compensating controls for exposed systems while remediation is scheduled and verified
- Check relevant monitoring, detection, and logs for exposed assets that need extra review
- Track exceptions, retest remediated assets, and close the item only after evidence is documented
Evidence notes
CVE-2026-66485: GNU cpio vulnerable to uncontrolled memory allocation; fix in commit 3cd514031371d8aeeaf2048aa10103e02831aaa9; evidence from official CVE record and NVD detail. The vulnerability allows for a denial of service via crafted archive. Users should verify their GNU cpio installations and ensure they are not exposed to untrusted archive sources.
Official resources
AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-08-10T11:17:27.773Z and has not been modified since then.