CVE-2026-31516: Linux kernel · xfrm: prevent policy_hthresh.work from racing with netns teardown
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 22 Apr 2026
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
Upgrade Linux kernel to 8854e9367465d784046362698731c1111e3b39b8, 56ea2257b83ee29a543f158159e3d1abc1e3e4fe, 29fe3a61bcdce398ee3955101c39f89c01a8a77e or 4e2e77843fef473ef47e322d52436d8308582a96.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| 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
- git.kernel.org/stable/c/56ea2257b83ee29a543f158159e3d1abc1e3e4fe (opens in a new tab)
- git.kernel.org/stable/c/8854e9367465d784046362698731c1111e3b39b8 (opens in a new tab)
- git.kernel.org/stable/c/4e2e77843fef473ef47e322d52436d8308582a96 (opens in a new tab)
- git.kernel.org/stable/c/29fe3a61bcdce398ee3955101c39f89c01a8a77e (opens in a new tab)