CVE-2026-97523 mptcp: close race between scheduler and state change
A race condition in the Linux kernel MPTCP scheduler can cause a division by zero, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-97523?
CVE-2026-97523 is a high-severity vulnerability in Linux, published on 25 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
mptcp: close race between scheduler and state change
The mptcp scheduler may race with subflow sockets state change: data transmission on the selected socket may fail and a later release could try to use mss_now reset to 0 for a divide operation.
Address the issue by explicitly checking for the critical scenario.
Which versions are affected by CVE-2026-97523?
How do I fix CVE-2026-97523?
Apply the vendor's patch.
Is CVE-2026-97523 being exploited?
There is no known exploitation of CVE-2026-97523 in the wild and no public exploit code.
Sources
Also known as AZL-104618, BELL-CVE-2026-97523, DEBIAN-CVE-2026-97523, GHSA-7c5c-gph2-xxg8, UBUNTU-CVE-2026-97523.