CVE-2026-43451 netfilter: nfnetlink_queue: fix entry leak in bridge verdict error path
A memory leak in the Linux kernel netfilter bridge verdict path allows attackers to exhaust kernel memory, causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43451?
CVE-2026-43451 is a medium-severity denial of service vulnerability in Linux kernel, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nfnetlink_queue: fix entry leak in bridge verdict error path
nfqnl_recv_verdict() calls find_dequeue_entry() to remove the queue entry from the queue data structures, taking ownership of the entry. For PF_BRIDGE packets, it then calls nfqa_parse_bridge() to parse VLAN attributes. If nfqa_parse_bridge() returns an error (e.g. NFQA_VLAN present but NFQA_VLAN_TCI missing), the function returns immediately without freeing the dequeued entry or its sk_buff.
This leaks the nf_queue_entry, its associated sk_buff, and all held references (net_device refcounts, struct net refcount). Repeated triggering exhausts kernel memory.
Fix this by dropping the entry via nfqnl_reinject() with NF_DROP verdict on the error path, consistent with other error handling in this file.
Weakness: CWE-401
Which versions are affected by CVE-2026-43451?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43451?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-43451 being exploited?
There is no known exploitation of CVE-2026-43451 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43451, DEBIAN-CVE-2026-43451, GHSA-hx98-q4r6-mgcv, ROOT-OS-DEBIAN-11-CVE-2026-43451, ROOT-OS-UBUNTU-2204-CVE-2026-43451, ROOT-OS-UBUNTU-2404-CVE-2026-43451 and 1 more.