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

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-22 · updated 2026-10-19
Weakness: CWE-362

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: prevent policy_hthresh.work from racing with netns teardown A XFRM_MSG_NEWSPDINFO request can queue the per-net work item policy_hthresh.work onto the system workqueue. The queued callback, xfrm_hash_rebuild(), retrieves the enclosing struct net via container_of(). If the net namespace is torn down before that work runs, the associated struct net may already have been freed, and xfrm_hash_rebuild() may then dereference stale memory. xfrm_policy_fini() already flushes policy_hash_work during teardown, but it does not synchronize policy_hthresh.work. Synchronize policy_hthresh.work in xfrm_policy_fini() as well, so the queued work cannot outlive the net namespace teardown and access a freed struct net.

Affected products

Linux kernel: from 3.18.1 before 6.12.80; from 6.13 before 6.18.21; from 6.19 before 6.19.11; 3.18, 7.0-rc1, 7.0-rc2, 7.0-rc3, 7.0-rc4, 7.0-rc5 (+2) — fixed in 6.12.80, 6.18.21, 6.19.11

How to fix

Upgrade to a fixed version: Linux kernel 6.12.80, 6.18.21, 6.19.11. Check the vendor advisory for mitigations.

References

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