CVE-2026-72243 selinux: check connect-related permissions on TCP Fast Open
Attackers can bypass SELinux connect permissions when using TCP Fast Open, allowing unauthorized network connections.
- 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-2026-72243?
CVE-2026-72243 is a high-severity missing authorization vulnerability in Linux, published on 15 Aug 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:
selinux: check connect-related permissions on TCP Fast Open
Similar to Landlock, SELinux was not updated when TCP Fast Open support was introduced to ensure connect-related permissions are checked when using TCP Fast Open. Update its socket_sendmsg() hook to call selinux_socket_connect() when MSG_FASTOPEN is passed.
Which versions are affected by CVE-2026-72243?
How do I fix CVE-2026-72243?
Apply the vendor's patch.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-72243 being exploited?
There is no known exploitation of CVE-2026-72243 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72243, DEBIAN-CVE-2026-72243, GHSA-m92q-543g-vq9x, UBUNTU-CVE-2026-72243.