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VulnerabilityPublished Updated

CVE-2025-40271: Linux kernel · fs/proc: fix uaf in proc_readdir_de()

Source GCVE Database

0

Public exploit available (Exploit-DB) · CVSS 7.8 High.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 39% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

  1. Disclosed: evidence found.

    CVE published 7 Dec 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

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

    Not in CISA KEV and no source reports exploitation

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

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE published

    on cve.org

    , t = 0

  2. First Exploit-DB entry (opens in a new tab)

    Linux Kernel proc_readdir_de() 6.18-rc5 - Local Privilege Escalation

    , 148 days after disclosure

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 26 Oct 2026.

What to do

AI-suggested

Since this is a kernel vulnerability, remediation typically involves applying an official kernel update that includes the fix to clear the erased node properly. Until a patch is applied, avoid running untrusted code that can trigger concurrent directory traversal and device unregistration operations. Monitor vendor advisories for official fixes.

Description

A use-after-free (UAF) vulnerability was identified and resolved in the Linux kernel's proc filesystem code, specifically in the proc_readdir_de() function. The issue occurs because a directory entry node (pde) is erased from a red-black tree but not properly cleared, leading to potential access of freed memory during directory traversal. This can happen when network devices are unregistered concurrently with directory reads under /proc, causing the kernel to access released memory. The vulnerability was discovered through stress testing and involves a race condition between directory iteration and device unregistration.

References

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