CVE-2025-21893
Linux Kernel Keyring Use After Free (UAF) Vulnerability
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.
INFO
Published Date :
March 31, 2025, 8:15 p.m.
Last Modified :
April 8, 2025, 3:48 p.m.
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Remotely Exploitable :
No
Impact Score :
5.9
Exploitability Score :
1.8
Public PoC/Exploit Available at Github
CVE-2025-21893 has a 1 public PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-21893.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Module 1 of Prober tool.
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-21893 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-21893 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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Initial Analysis by [email protected]
Apr. 08, 2025
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.13.9 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.10 up to (excluding) 6.12.21 Added Reference Type kernel.org: https://git.kernel.org/stable/c/6afe2ea2daec156bd94ad2c5a6f4f4c48240dcd3 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/75845c6c1a64483e9985302793dbf0dfa5f71e32 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/f6a3cf833188e897c97028cd7b926e3f2cb1a8c0 Types: Patch -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Mar. 31, 2025
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-416 -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Mar. 31, 2025
Action Type Old Value New Value Added 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. Added Reference https://git.kernel.org/stable/c/6afe2ea2daec156bd94ad2c5a6f4f4c48240dcd3 Added Reference https://git.kernel.org/stable/c/75845c6c1a64483e9985302793dbf0dfa5f71e32 Added Reference https://git.kernel.org/stable/c/f6a3cf833188e897c97028cd7b926e3f2cb1a8c0
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-21893 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-21893
weaknesses.