CVE-2026-23392

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_tables: release flowtable after rcu grace period on error

Call synchronize_rcu() after unregistering the hooks from error path, since a hook that already refers to this flowtable can be already registered, exposing this flowtable to packet path and nfnetlink_hook control plane.

This error path is rare, it should only happen by reaching the maximum number hooks or by failing to set up to hardware offload, just call synchronize_rcu().

There is a check for already used device hooks by different flowtable that could result in EEXIST at this late stage. The hook parser can be updated to perform this check earlier to this error path really becomes rarely exercised.

Uncovered by KASAN reported as use-after-free from nfnetlink_hook path when dumping hooks.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/7e3955b282eae20d61c75e499c75eade51c20060
• https://git.kernel.org/stable/c/adee3436ccd29f1e514c028899e400cbc6d84065
• https://git.kernel.org/stable/c/c8092edb9a11f20f95ccceeb9422b7dd0df337bd
• https://git.kernel.org/stable/c/d2632de96ccb066e0131ad1494241b9c281c60b8
• https://git.kernel.org/stable/c/d73f4b53aaaea4c95f245e491aa5eeb8a21874ce
• https://git.kernel.org/stable/c/e78a2dcc7cfb87b64a631441ca7681492b347ef6