CVE-2025-21893

Description

In the Linux kernel, the following vulnerability has been resolved: keys: Fix UAF in key_put() Once a key's reference count has been reduced to 0, the garbage collector thread may destroy it at any time and so key_put() is not allowed to touch the key after that point. The most key_put() is normally allowed to do is to touch key_gc_work as that's a static global variable. However, in an effort to speed up the reclamation of quota, this is now done in key_put() once the key's usage is reduced to 0 - but now the code is looking at the key after the deadline, which is forbidden. Fix this by using a flag to indicate that a key can be gc'd now rather than looking at the key's refcount in the garbage collector.

CVSS Metrics

• v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.05%• Percentile: 15%

Techniques & Countermeasures

• CWE-416•Use After Free

  The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Affected Systems

• linux•linux

  ≥ 9578e327b2b4935a25d49e3891b8fcca9b6c10c6, < 6afe2ea2daec156bd94ad2c5a6f4f4c48240dcd3 | ≥ 9578e327b2b4935a25d49e3891b8fcca9b6c10c6, < f6a3cf833188e897c97028cd7b926e3f2cb1a8c0 | ≥ 9578e327b2b4935a25d49e3891b8fcca9b6c10c6, < 75845c6c1a64483e9985302793dbf0dfa5f71e32 | 6.10

• linux•linux_kernel

  ≥ 6.10, < 6.12.21 | ≥ 6.13, < 6.13.9 | 6.14:rc1 | 6.14:rc2 | 6.14:rc3 | 6.14:rc4

References (3)

• https://git.kernel.org/stable/c/6afe2ea2daec156bd94ad2c5a6f4f4c48240dcd3
• https://git.kernel.org/stable/c/f6a3cf833188e897c97028cd7b926e3f2cb1a8c0
• https://git.kernel.org/stable/c/75845c6c1a64483e9985302793dbf0dfa5f71e32