openvswitch: Fix CT limit teardown use-after-free

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89488
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:30 UTC
Updated2026-09-11 20:19:30 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: openvswitch: Fix CT limit teardown use-after-free Packet processing uses CT limit state under RCU, while netns teardown frees that state under ovs_mutex. The CT limit pointer was neither removed from readers nor protected by a grace period, allowing packet processing to dereference the freed state. An unprivileged user can trigger this bug from a user and network namespace, causing a slab-use-after-free in ovs_ct_execute() when the netns is torn down. Publish the CT limit pointer through RCU, remove it before teardown, and wait for readers before freeing its contents. Keep ovs_mutex around individual CT limit updates, and use the RCU read-side lock while GET traverses the RCU-protected limit lists. Netns teardown detaches the RCU-protected CT limit state in the pernet .pre_exit callback while holding ovs_mutex. The pernet core guarantees an RCU grace period between the .pre_exit and .exit callbacks, so the .exit callback completes the teardown without adding any extra synchronization. The netlink command handlers do not need NULL checks because the userspace netlink socket holds an active reference to its network namespace while a request is processed. The per-netns exit path therefore cannot run concurrently with SET, DEL, or GET for that socket's namespace.

Risk And Classification

EPSS: 0.001660000 probability, percentile 0.061360000 (date 2026-09-12)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 11efd5cb04a184eea4f57b68ea63dddd463158d1 e15407c3a8a005324f633cd46cd8fb58042c1157 git Not specified
CNA Linux Linux affected 11efd5cb04a184eea4f57b68ea63dddd463158d1 6a6d36fadb8537d9b79e72c9fa51885ec0c33e10 git Not specified
CNA Linux Linux affected 11efd5cb04a184eea4f57b68ea63dddd463158d1 403f96c32c9e24600093d7d0c61c17daeedca957 git Not specified
CNA Linux Linux affected 4.18 Not specified
CNA Linux Linux unaffected 4.18 semver Not specified
CNA Linux Linux unaffected 6.18.51 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/e15407c3a8a005324f633cd46cd8fb58042c1157 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6a6d36fadb8537d9b79e72c9fa51885ec0c33e10 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/403f96c32c9e24600093d7d0c61c17daeedca957 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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