# CVE-2026-66485: Uncontrolled Memory Allocation in GNU cpio

> A malicious cpio archive can cause a stack overflow and crash the cpio process during extraction, leading to denial of service.

- **Severity:** Medium 4.6 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 10 Aug 2026
- **Also known as:** AZL-94692, DEBIAN-CVE-2026-66485, GHSA-mmw4-f4p6-w77q, RHSA-2026:82414, UBUNTU-CVE-2026-66485

## What is CVE-2026-66485?

CVE-2026-66485 is a medium-severity denial of service vulnerability in GNU cpio, published on 10 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official 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

Weakness: CWE-789 (Memory Allocation with Excessive Size Value)

## Which versions are affected by CVE-2026-66485?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `cpio` | Red Hat:hummingbird:1 | All versions | 0:2.15-10.3.hum1 |

## How do I fix CVE-2026-66485?

Apply the vendor's patch.

## Is CVE-2026-66485 being exploited?

There is no known exploitation of CVE-2026-66485 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-66485 and fix it if it is affected.

What it is: CVE-2026-66485 is a medium-severity denial of service vulnerability in GNU cpio, published on 10 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-66485 in the wild and no public exploit code.

Affected product: GNU cpio. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-66485/ (Markdown: https://insights.sbomify.com/CVE-2026-66485/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66485
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66485
- OSV: https://osv.dev/vulnerability/CVE-2026-66485

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-66485/
Summaries are generated and may contain mistakes; the official description above is the record.