CVE-2026-43084 netfilter: nfnetlink_queue: make hash table per queue
A use-after-free vulnerability in the Linux kernel netfilter module allows attackers to cause a crash or potentially execute code via race conditions.
- 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-2026-43084?
CVE-2026-43084 is a high-severity use after free vulnerability in Linux kernel, published on 6 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: make hash table per queue
Sharing a global hash table among all queues is tempting, but it can cause crash:
BUG: KASAN: slab-use-after-free in nfqnl_recv_verdict+0x11ac/0x15e0 [nfnetlink_queue] [..] nfqnl_recv_verdict+0x11ac/0x15e0 [nfnetlink_queue] nfnetlink_rcv_msg+0x46a/0x930 kmem_cache_alloc_node_noprof+0x11e/0x450
struct nf_queue_entry is freed via kfree, but parallel cpu can still encounter such an nf_queue_entry when walking the list.
Alternative fix is to free the nf_queue_entry via kfree_rcu() instead, but as we have to alloc/free for each skb this will cause more mem pressure.
Weakness: CWE-416
Which versions are affected by CVE-2026-43084?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43084?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-43084 being exploited?
There is no known exploitation of CVE-2026-43084 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43084, DEBIAN-CVE-2026-43084, GHSA-2xw5-2v9x-wc8m, ROOT-OS-UBUNTU-2404-CVE-2026-43084, UBUNTU-CVE-2026-43084.