CVE-2026-23272 netfilter: nf_tables: unconditionally bump set->nelems before insertion
A use-after-free vulnerability in the Linux kernel netfilter subsystem allows attackers to potentially execute code or escalate privileges.
- 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-2026-23272?
CVE-2026-23272 is a high-severity use after free vulnerability in Linux kernel, published on 20 Mar 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: nf_tables: unconditionally bump set->nelems before insertion
In case that the set is full, a new element gets published then removed without waiting for the RCU grace period, while RCU reader can be walking over it already.
To address this issue, add the element transaction even if set is full, but toggle the set_full flag to report -ENFILE so the abort path safely unwinds the set to its previous state.
As for element updates, decrement set->nelems to restore it.
A simpler fix is to call synchronize_rcu() in the error path. However, with a large batch adding elements to already maxed-out set, this could cause noticeable slowdown of such batches.
Weakness: CWE-416
Which versions are affected by CVE-2026-23272?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23272?
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-2026-23272 being exploited?
There is no known exploitation of CVE-2026-23272 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-80210, BELL-CVE-2026-23272, DEBIAN-CVE-2026-23272, GHSA-qhvv-4mw5-pxh3, ROOT-OS-DEBIAN-11-CVE-2026-23272, ROOT-OS-DEBIAN-12-CVE-2026-23272 and 4 more.