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CVE-2025-40215VulnerabilityPublished Updated

CVE-2025-40215: Linux kernel · xfrm: delete x->tunnel as we delete x The ipcomp fallback tunnels currently get

Source GCVE Database

0

Not known to be exploited · CVSS 7.8 High.

Data as of 25 Oct 2026, 19:02 UTC

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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 4 Dec 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 2026-10-25.

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

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