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VulnerabilityPublished Updated

CVE-2026-31516: Linux kernel · xfrm: prevent policy_hthresh.work from racing with netns teardown

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in 8854e9367465d784046362698731c1111e3b39b8 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 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 0% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in 8854e9367465d784046362698731c1111e3b39b8, 56ea2257b83ee29a543f158159e3d1abc1e3e4fe, 29fe3a61bcdce398ee3955101c39f89c01a8a77e +1
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 22 Apr 2026

  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 26 Oct 2026.

What to do

Upgrade Linux kernel to 8854e9367465d784046362698731c1111e3b39b8, 56ea2257b83ee29a543f158159e3d1abc1e3e4fe, 29fe3a61bcdce398ee3955101c39f89c01a8a77e or 4e2e77843fef473ef47e322d52436d8308582a96.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 880a6fab8f6ba5b5abe59ea68533202ddea1012c, < 8854e9367465d784046362698731c1111e3b39b8
Fixed in
  • 8854e9367465d784046362698731c1111e3b39b8
LinuxLinuxAffected
  • ≥ 880a6fab8f6ba5b5abe59ea68533202ddea1012c, < 56ea2257b83ee29a543f158159e3d1abc1e3e4fe
Fixed in
  • 56ea2257b83ee29a543f158159e3d1abc1e3e4fe
LinuxLinuxAffected
  • ≥ 880a6fab8f6ba5b5abe59ea68533202ddea1012c, < 29fe3a61bcdce398ee3955101c39f89c01a8a77e
Fixed in
  • 29fe3a61bcdce398ee3955101c39f89c01a8a77e
LinuxLinuxAffected
  • ≥ 880a6fab8f6ba5b5abe59ea68533202ddea1012c, < 4e2e77843fef473ef47e322d52436d8308582a96
Fixed in
  • 4e2e77843fef473ef47e322d52436d8308582a96
LinuxLinuxAffected
  • =3.18
Fixed in–

AI-suggested

A fix is available and has been applied in the Linux kernel. Users should update to a fixed kernel version that includes the synchronization of policy_hthresh.work during network namespace teardown. No additional mitigation is required once the patch is applied.

Description

CVE-2026-31516 is a use-after-free vulnerability in the Linux kernel's XFRM subsystem related to race conditions during network namespace teardown. The issue occurs because a work item (policy_hthresh.work) can be queued and executed after the associated network namespace has been freed, leading to dereferencing stale memory. This flaw has been fixed by synchronizing the work item during teardown to prevent it from outliving the network namespace.

References

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