CVE-2026-80628 ALSA: seq: oss: Serialize readq reset state with q->lock
A race condition in the Linux kernel ALSA OSS sequencer allows attackers to corrupt queue state, potentially causing denial of service or information disclosure.
- 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-2026-80628?
CVE-2026-80628 is a high-severity vulnerability in Linux, published on 28 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: seq: oss: Serialize readq reset state with q->lock
snd_seq_oss_readq_clear() resets qlen, head, and tail without q->lock even though the normal reader and producer paths serialize the same ring state under that spinlock. A reset can therefore race snd_seq_oss_readq_free() or snd_seq_oss_readq_put_event() and leave stale records in the queue, drop freshly queued ones, or report the wrong readiness after wakeup. KCSAN reports a data race between snd_seq_oss_readq_clear() and snd_seq_oss_readq_free().
Take q->lock while clearing the ring and resetting input_time. Factor the enqueue logic into a caller-locked helper so snd_seq_oss_readq_put_timestamp() updates its suppression state under the same lock instead of racing the reset path.
The buggy scenario involves two paths, with each column showing the order within that path:
reset path: locked readq updater: 1. snd_seq_oss_reset() or 1. A reader or callback producer release reaches takes q->lock on the same queue. snd_seq_oss_readq_clear(). 2. snd_seq_oss_readq_clear() 2. The updater tests or modifies resets qlen, head, tail, qlen, head, and tail. and input_time. 3. snd_seq_oss_readq_clear() 3. The updater completes its wakes sleepers on read-modify-write sequence. q->midi_sleep. 4. Without q->lock, the reset 4. The resulting ring state drives can overlap the locked later reads and readiness. update.
KCSAN reports:
BUG: KCSAN: data-race in snd_seq_oss_readq_clear / snd_seq_oss_readq_free
write to 0xffff8881069fe608 of 4 bytes by task 120516 on cpu 0: snd_seq_oss_readq_free+0x6c/0x80 snd_seq_oss_read+0xcb/0x250 odev_read+0x38/0x60 vfs_read+0xff/0x600 ksys_read+0xb4/0x140 __x64_sys_read+0x46/0x60 do_syscall_64+0xbb/0x2f0 entry_SYSCALL_64_after_hwframe+0x77/0x7f
read to 0xffff8881069fe608 of 4 bytes by task 120517 on cpu 1: snd_seq_oss_readq_clear+0x1f/0x90 snd_seq_oss_reset+0xa7/0xf0 snd_seq_oss_ioctl+0x6f6/0x7e0 odev_ioctl+0x56/0xc0 __x64_sys_ioctl+0xd1/0x120 do_syscall_64+0xbb/0x2f0 entry_SYSCALL_64_after_hwframe+0x77/0x7f
value changed: 0x00000001 -> 0x00000000
Which versions are affected by CVE-2026-80628?
How do I fix CVE-2026-80628?
Apply the vendor's patch.
Is CVE-2026-80628 being exploited?
There is no known exploitation of CVE-2026-80628 in the wild and no public exploit code.
Sources
Also known as AZL-98145, BELL-CVE-2026-80628, DEBIAN-CVE-2026-80628, GHSA-g7mq-rrq4-x494, UBUNTU-CVE-2026-80628.