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VulnerabilityPublished Updated

CVE-2025-21999: Linux kernel · proc: fix UAF in proc_get_inode()

Affects Linux kernelSource GCVE Database

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Not known to be exploited · CVSS 7.8 High.

Data as of 10 Nov 2026, 13:47 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.

Sources agree

CVSS scores by source
CNA (Linux)CVSS 3.17.8
CISA-ADPCVSS 3.17.8
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Apr 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel. Users and administrators should apply the official kernel updates that include this patch to resolve the use-after-free condition in proc_get_inode(). No additional mitigation steps are required once the patch is applied.

Description

CVE-2025-21999 is a use-after-free (UAF) vulnerability in the Linux kernel's proc filesystem, specifically in the proc_get_inode() function. The flaw arises from a race condition between module removal (rmmod) and inode instantiation for /proc entries. Dereferencing proc_ops of a module after it has been freed leads to a kernel crash (use-after-free).

References

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