CVE-2026-97568 mptcp: syncookies: remember the request backup flag
An uninitialized memory read in the Linux kernel MPTCP subsystem may leak sensitive kernel memory to remote attackers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-97568?
CVE-2026-97568 is a 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: syncookies: remember the request backup flag
Instead of using an uninitialised bit when copying the info in subflow_ulp_clone().
To fix this, no need to extend the join_entry structure: backup is coming from struct mptcp_subflow_request_sock, only one bit. Do the same here by using one bit for both.
Which versions are affected by CVE-2026-97568?
How do I fix CVE-2026-97568?
Apply the vendor's patch.
Is CVE-2026-97568 being exploited?
There is no known exploitation of CVE-2026-97568 in the wild and no public exploit code.
Sources
Also known as AZL-104529, BELL-CVE-2026-97568, DEBIAN-CVE-2026-97568, GHSA-6cg2-hrxf-655w, UBUNTU-CVE-2026-97568.