Use After Free in Linux
CVE-2025-21893
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.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.002 (8.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 8th percentile — 8.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Linux — versions 9578e327b2b4935a25d49e3891b8fcca9b6c10c6, 6.10, 0
- Linux Kernel — versions 6.14
Weakness classification (CWE)
Public proof-of-concept exploits
References
Frequently asked questions
- What is CVE-2025-21893?
- CVE-2025-21893 is a high-severity vulnerability in Linux, classified under Use After Free. CVSS score: 7.8/10. Published 2025-03-31.
- How severe is CVE-2025-21893?
- High severity. CVSS v3 base score is 7.8 out of 10.
- Is CVE-2025-21893 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.