CVE-2025-40215: Linux kernel · xfrm: delete x->tunnel as we delete x
Source GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% 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
Disclosed: evidence found.
CVE published 4 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
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
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
The description indicates a patch has been developed to fix the issue by changing the deletion timing of fallback states. Until an official fix is confirmed, monitoring vendor advisories for updates and applying kernel updates promptly when available is recommended.
Description
A vulnerability in the Linux kernel's xfrm subsystem involves improper deletion of ipcomp fallback tunnels, which can lead to references remaining in kernel data structures and triggering warnings. The issue arises because fallback tunnels are deleted only when the last user state is destroyed, but references may still exist, preventing timely cleanup. This can occur due to deferred freeing of socket buffers (skbs) in TCP and IP reassembly scenarios. The fix involves deleting the fallback state immediately after the last dependent user state is deleted, ensuring proper resource cleanup and avoiding kernel warnings.
References
- nvd.nist.gov/vuln/detail/CVE-2025-40215 (opens in a new tab)
- git.kernel.org/stable/c/0da961fa46da1b37ef868d9b603bd202136f8f8e (opens in a new tab)
- git.kernel.org/stable/c/1b28a7fae0128fa140a7dccd995182ff6cd1c67b (opens in a new tab)
- git.kernel.org/stable/c/4b2c17d0f9be8b58bb30468bc81a4b61c985b04e (opens in a new tab)
- git.kernel.org/stable/c/b441cf3f8c4b8576639d20c8eb4aa32917602ecd (opens in a new tab)
- git.kernel.org/stable/c/d0e0d1097118461463b76562c7ebaabaa5b90b13 (opens in a new tab)
- git.kernel.org/stable/c/dc3636912d41770466543623cb76e7b88fdb42c7 (opens in a new tab)