CVE-2026-46170 mptcp: pm: ADD_ADDR rtx: free sk if last
A use-after-free vulnerability in the Linux kernel MPTCP path manager allows attackers to cause a denial of service via improper socket reference counting during retransmissions.
- 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-2026-46170?
CVE-2026-46170 is a medium-severity use after free vulnerability in Linux kernel, published on 28 May 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:
mptcp: pm: ADD_ADDR rtx: free sk if last
When an ADD_ADDR is retransmitted, the sk is held in sk_reset_timer(), and released at the end.
If at that moment, it was the last reference being held, the sk would not be freed. sock_put() should then be called instead of __sock_put().
But that's not enough: if it is the last reference, sock_put() will call sk_free(), which will end up calling sk_stop_timer_sync() on the same timer, and waiting indefinitely to finish. So it is needed to mark that the timer is done at the end of the timer handler when it has not been rescheduled, not to call sk_stop_timer_sync() on "itself".
Which versions are affected by CVE-2026-46170?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46170?
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-2026-46170 being exploited?
There is no known exploitation of CVE-2026-46170 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-89091, BELL-CVE-2026-46170, DEBIAN-CVE-2026-46170, GHSA-xrpw-xx6g-3jg3, ROOT-OS-DEBIAN-11-CVE-2026-46170, ROOT-OS-DEBIAN-12-CVE-2026-46170 and 4 more.