CVE-2025-21893: keys: Fix UAF in key_put()
First published: Mon Mar 31 2025(Updated: )
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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | ||
| Linux Kernel | >=6.10<6.12.21 | |
| Linux Kernel | >=6.13<6.13.9 | |
| Linux Kernel | =6.14-rc1 | |
| Linux Kernel | =6.14-rc2 | |
| Linux Kernel | =6.14-rc3 | |
| Linux Kernel | =6.14-rc4 |
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Reference Links
Frequently Asked Questions
What is the severity of CVE-2025-21893?
CVE-2025-21893 is classified as a high-severity vulnerability impacting the Linux kernel.
How do I fix CVE-2025-21893?
To fix CVE-2025-21893, update your Linux kernel to the latest patched version provided by your distribution.
What systems are affected by CVE-2025-21893?
CVE-2025-21893 affects various versions of the Linux kernel used in many Linux distributions.
What type of vulnerability is CVE-2025-21893?
CVE-2025-21893 is a use-after-free (UAF) vulnerability in the key management feature of the Linux kernel.
What are the potential risks of CVE-2025-21893?
Exploitation of CVE-2025-21893 may lead to arbitrary code execution or system crashes.
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