# CVE-2026-66486: GNU cpio improper encoding of archive listing output

Source: https://junglewise.ai/threats/cve-2026-66486-gnu-cpio-improper-encoding-of-archive-listing-output  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-10. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-66486 · Severity: info · CVSS 0 · Published 2026-08-10

GNU cpio is a standard archiving utility used to extract and manage backup files. When listing archive contents with the -it flag, the tool can display crafted malicious filenames containing hidden characters or control sequences that trick users or compromise terminal security, potentially causing display manipulation or injection attacks.

Technologies: [Gnu Cpio](https://junglewise.ai/threats/technologies/cpio). Vendors: [Gnu](https://junglewise.ai/threats/vendors/gnu).

## Quick answers

**Is CVE-2026-66486 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-66486 being exploited in the wild.

**How severe is CVE-2026-66486?** Informational severity, with a CVSS score of 0, published 10 August 2026.

**Which products and versions are affected?** Gnu Cpio through 2.15.

**Is there a fix for CVE-2026-66486?** A patch was published on 2026-07-23: Fix released in commit 2ff9600c9ef32e88759843cdbde74c8db5ae9b30 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-66486 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-66486?** Check whether you run Gnu Cpio at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This vulnerability is a CWE-116 improper encoding/escaping flaw in cpio's archive member listing functionality. When cpio lists archive members via the -it command, member names are printed directly to output without quoting or escaping special characters. An attacker can craft a malicious cpio archive with member names containing embedded newline characters or ANSI escape sequences. These are rendered unescaped during listing, allowing injection of forged listing entries or terminal control sequences that manipulate terminal behavior. The issue is fixed in commit 2ff9600c9ef32e88759843cdbde74c8db5ae9b30 and affects cpio versions through 2.15.

## Affected products

- GNU cpio through 2.15

## Timeline

- 2026-08-10: disclosed
- 2026-07-23: patched: Fix released in commit 2ff9600c9ef32e88759843cdbde74c8db5ae9b30

## References

- [https://cert.pl/en/posts/2026/08/CVE-2026-66484](https://cert.pl/en/posts/2026/08/CVE-2026-66484)
- [https://git.savannah.gnu.org/cgit/cpio.git](https://git.savannah.gnu.org/cgit/cpio.git)

## Related threats

- [cpio stack-based buffer overflow in tar header](https://junglewise.ai/threats/cve-2026-126831-a-flaw-was-found-in-cpio-a-local-user-can-cause-a-denial-of)
- [GNU cpio uncontrolled stack memory allocation in make_path](https://junglewise.ai/threats/cve-2026-66485-gnu-cpio-uncontrolled-stack-memory-allocation-in-make-path)
- [GNU cpio path traversal in tar hard-link extraction](https://junglewise.ai/threats/cve-2026-66484-gnu-cpio-path-traversal-in-tar-hard-link-extraction)
- [GNU cpio insecure file permissions via 0 umask in archive creation](https://junglewise.ai/threats/cve-1999-1572-gnu-cpio-insecure-file-permissions-via-0-umask-in-archive-creation)