REDHAT-BUG-2451218: Use After Free
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nftables: release flowtable after rcu grace period on error
Call synchronizercu() 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 nfnetlinkhook 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 synchronizercu().
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 nfnetlinkhook path when dumping hooks.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Apply a source-level fix to the netfilter nf_tables code: after unregistering hooks on the error path, call synchronize_rcu() to wait for an RCU grace period so that any hook still referring to the flowtable cannot be used from the packet path or nfnetlink_hook control plane.
- Compensating control
Update the hook parser to perform the check for already-used device hooks earlier in processing so that a conflicting hook (which would later result in EEXIST on this late error path) is detected before reaching the hardware offload/unregister error path.
Event History
Frequently Asked Questions
What is the severity of REDHAT-BUG-2451218?
The severity of REDHAT-BUG-2451218 is medium with a score of 4.
How do I fix REDHAT-BUG-2451218?
To address REDHAT-BUG-2451218, ensure that the Linux kernel is updated to the patched version provided by The Linux Foundation.
What type of vulnerability is REDHAT-BUG-2451218?
REDHAT-BUG-2451218 is categorized as a Use After Free vulnerability.
What software is affected by REDHAT-BUG-2451218?
The affected software for REDHAT-BUG-2451218 is the Linux kernel specifically related to netfilter nf_tables.
When was REDHAT-BUG-2451218 published?
REDHAT-BUG-2451218 was published on March 25, 2026.