Linux Kernel nf_tables Use-After-Free on RCU-Unsync Hook Path
CVE-2026-23392 Published on March 25, 2026
netfilter: nf_tables: release flowtable after rcu grace period on error
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.
Products Associated with CVE-2026-23392
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Affected Versions
Linux:- Version 3b49e2e94e6ebb8b23d0955d9e898254455734f8 and below d2632de96ccb066e0131ad1494241b9c281c60b8 is affected.
- Version 3b49e2e94e6ebb8b23d0955d9e898254455734f8 and below adee3436ccd29f1e514c028899e400cbc6d84065 is affected.
- Version 3b49e2e94e6ebb8b23d0955d9e898254455734f8 and below 7e3955b282eae20d61c75e499c75eade51c20060 is affected.
- Version 3b49e2e94e6ebb8b23d0955d9e898254455734f8 and below c8092edb9a11f20f95ccceeb9422b7dd0df337bd is affected.
- Version 3b49e2e94e6ebb8b23d0955d9e898254455734f8 and below e78a2dcc7cfb87b64a631441ca7681492b347ef6 is affected.
- Version 3b49e2e94e6ebb8b23d0955d9e898254455734f8 and below d73f4b53aaaea4c95f245e491aa5eeb8a21874ce is affected.
- Version 4.16 is affected.
- Before 4.16 is unaffected.
- Version 6.1.167, <= 6.1.* is unaffected.
- Version 6.6.130, <= 6.6.* is unaffected.
- Version 6.12.78, <= 6.12.* is unaffected.
- Version 6.18.20, <= 6.18.* is unaffected.
- Version 6.19.10, <= 6.19.* is unaffected.
- Version 7.0-rc5, <= * is unaffected.