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

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-12-24 · updated 2026-10-15

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.

Affected products

• Linux kernel: 2.6.34 — fixed in 6.4

How to fix

Upgrade to a fixed version: Linux kernel 6.4. Check the vendor advisory for mitigations.

References

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

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