{"apiVersion":"1.0","identifier":"CVE-2026-74503","description":"In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes snd_timer_close_locked() marks an instance with SNDRV_TIMER_IFLG_DEAD and returns early when the flag is already set, but the flag is never cleared again. A completed close ends in remove_slave_links(), which leaves timeri->timer NULL, so a second close is already harmless through the timer == NULL path; the early return can only be reached by an instance that was opened again in between. For such an instance the close unlinks nothing, so snd_timer_instance_free() frees an object that is still on timer->open_list_head, still on snd_timer_master_list if it was opened with a slave key, still owns any adopted slaves, and still holds its timer and module references. snd_seq_timer_open() reopens an instance exactly like that: it retries its fallback open on the same object after a failure that has already run snd_timer_close_locked() internally. An unprivileged user with access to /dev/snd/timer and /dev/snd/seq can force that failure, since snd_timer_check_master() returns -EBUSY when a pending slave matches the new master-s (slave_class, slave_id) key and the target timer has reached max_instances, and SNDRV_TIMER_IOCTL_SELECT with dev_class = SNDRV_TIMER_CLASS_SLAVE keeps the caller-supplied dev_sclass, so a sequencer queue-s key can be forged. The freed instance is afterwards dereferenced by any further snd_timer_open() on that timer, by snd_timer_check_slave(), and by /proc/asound/timers, which faults on the stale ti->owner pointer. The flag only has to be visible while the close is in progress, which is all its other users need. Clear it in remove_slave_links(), under the same timer->lock that sets it, once the instance is off every list.","publishedAt":"2026-08-15T13:17:55","lastModifiedAt":"2026-08-17T06:19:46","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74503","cvssScore":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","epssProbability":0.00129,"riskScore":0.79,"affectedProduct":"linux","affectedVersions":"unknown","vulnerabilityType":"Kernel","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-74503","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-74503","en":"https://www.redsauce.net/en/cves/CVE-2026-74503","fr":"https://www.redsauce.net/fr/cves/CVE-2026-74503","pt":"https://www.redsauce.net/pt/cves/CVE-2026-74503","de":"https://www.redsauce.net/de/cves/CVE-2026-74503","sk":"https://www.redsauce.net/sk/cves/CVE-2026-74503","el":"https://www.redsauce.net/el/cves/CVE-2026-74503"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-74503"}}