CVE-2026-68201 ALSA: timer: drain a slave's callback before its master detaches it
A use-after-free in the Linux kernel ALSA timer allows local attackers to execute arbitrary code or escalate privileges when a master timer instance is closed while a slave callback is running.
- 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-2026-68201?
CVE-2026-68201 is a high-severity use after free vulnerability in Linux, published on 10 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:
ALSA: timer: drain a slave's callback before its master detaches it
snd_timer_close_locked() drains the closing instance's own in-flight callback (IFLG_CALLBACK) before freeing it, but not its slaves'. When a master instance is closed, remove_slave_links() clears each slave's ->timer; the slave's own close then reads timer == NULL and takes the branch that skips the drain entirely (snd_timer_stop_slave() also no-ops on a NULL timer). So a slave whose callback is still running when the master is closed is freed underneath the live callback, leading to use-after-free.
Drain the slaves too before remove_slave_links() severs them. snd_timer_stop() has already taken this instance off the active list, so no new slave callback can be queued. Take the slaves off the ack list so a pending one can't fire either, then wait for any that is already in flight.
Weakness: CWE-416
Which versions are affected by CVE-2026-68201?
How do I fix CVE-2026-68201?
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-2026-68201 being exploited?
There is no known exploitation of CVE-2026-68201 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68201, DEBIAN-CVE-2026-68201, GHSA-793q-4mv8-rvwh, UBUNTU-CVE-2026-68201.