CVE-2026-23391 netfilter: xt_CT: drop pending enqueued packets on template removal
A use-after-free in the Linux kernel netfilter module allows attackers to cause a denial of service or potentially execute code when netfilter templates are removed while packets are enqueued.
- 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-2026-23391?
CVE-2026-23391 is a high-severity use after free vulnerability in Linux kernel, published on 25 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: xt_CT: drop pending enqueued packets on template removal
Templates refer to objects that can go away while packets are sitting in nfqueue refer to:
- helper, this can be an issue on module removal. - timeout policy, nfnetlink_cttimeout might remove it.
The use of templates with zone and event cache filter are safe, since this just copies values.
Flush these enqueued packets in case the template rule gets removed.
Weakness: CWE-416
Which versions are affected by CVE-2026-23391?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23391?
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-2026-23391 being exploited?
There is no known exploitation of CVE-2026-23391 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-80567, BELL-CVE-2026-23391, DEBIAN-CVE-2026-23391, GHSA-qqcv-h6xq-mw7q, ROOT-OS-DEBIAN-11-CVE-2026-23391, ROOT-OS-DEBIAN-12-CVE-2026-23391 and 4 more.