CVE-2026-53269 netfilter: synproxy: add mutex to guard hook reference counting
Concurrent netfilter hook registration in Linux kernel synproxy can cause a race condition, potentially leading to system instability or 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-2026-53269?
CVE-2026-53269 is a medium-severity vulnerability in Linux kernel, published on 25 Jun 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: synproxy: add mutex to guard hook reference counting
As the synproxy infrastructure register netfilter hooks on-demand when a user adds the first iptables target or nftables expression, if done concurrently they can race each other.
Introduce a mutex to serialize the refcount control blocks access from both frontends. While a per namespace mutex might be more efficient, it is not needed for target/expression like SYNPROXY.
Which versions are affected by CVE-2026-53269?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53269?
Apply the vendor's patch.
Is CVE-2026-53269 being exploited?
There is no known exploitation of CVE-2026-53269 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53269, DEBIAN-CVE-2026-53269, GHSA-7m9q-85qj-rc4g, ROOT-OS-DEBIAN-11-CVE-2026-53269, ROOT-OS-DEBIAN-12-CVE-2026-53269, ROOT-OS-UBUNTU-2204-CVE-2026-53269 and 2 more.