CVE-2025-40271: Linux kernel · fs/proc: fix uaf in proc_readdir_de()
Source GCVE Database
Public exploit available (Exploit-DB) · CVSS 7.8 High.
Data as of 26 Oct 2026, 12:55 UTC
- 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:HExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 7 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE published
on cve.org
, t = 0
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
- nvd.nist.gov/vuln/detail/CVE-2025-40271 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-253495.html (opens in a new tab)
- git.kernel.org/stable/c/03de7ff197a3d0e17d0d5c58fdac99a63cba8110 (opens in a new tab)
- git.kernel.org/stable/c/1d1596d68a6f11d28f677eedf6cf5b17dbfeb491 (opens in a new tab)
- git.kernel.org/stable/c/4cba73c4c89219beef7685a47374bf88b1022369 (opens in a new tab)
- git.kernel.org/stable/c/623bb26127fb581a741e880e1e1a47d79aecb6f8 (opens in a new tab)
- git.kernel.org/stable/c/67272c11f379d9aa5e0f6b16286b9d89b3f76046 (opens in a new tab)
- git.kernel.org/stable/c/6f2482745e510ae1dacc9b090194b9c5f918d774 (opens in a new tab)
- git.kernel.org/stable/c/895b4c0c79b092d732544011c3cecaf7322c36a1 (opens in a new tab)
- git.kernel.org/stable/c/c81d0385500446efe48c305bbb83d47f2ae23a50 (opens in a new tab)