{"cve":"CVE-2026-74503","nvd":{"published":"2026-08-15T13:17:55.310","modified":"2026-10-16T20:17:32.927","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes\n\nsnd_timer_close_locked() marks an instance with SNDRV_TIMER_IFLG_DEAD\nand returns early when the flag is already set, but the flag is never\ncleared again.  A completed close ends in remove_slave_links(), which\nleaves timeri->timer NULL, so a second close is already harmless through\nthe timer == NULL path; the early return can only be reached by an\ninstance that was opened again in between.  For such an instance the\nclose unlinks nothing, so snd_timer_instance_free() frees an object that\nis still on timer->open_list_head, still on snd_timer_master_list if it\nwas opened with a slave key, still owns any adopted slaves, and still\nholds its timer and module references.\n\nsnd_seq_timer_open() reopens an instance exactly like that: it retries\nits fallback open on the same object after a failure that has already\nrun snd_timer_close_locked() internally.  An unprivileged user with\naccess to /dev/snd/timer and /dev/snd/seq can force that failure, since\nsnd_timer_check_master() returns -EBUSY when a pending slave matches the\nnew master's (slave_class, slave_id) key and the target timer has\nreached max_instances, and SNDRV_TIMER_IOCTL_SELECT with dev_class =\nSNDRV_TIMER_CLASS_SLAVE keeps the caller-supplied dev_sclass, so a\nsequencer queue's key can be forged.  The freed instance is afterwards\ndereferenced by any further snd_timer_open() on that timer, by\nsnd_timer_check_slave(), and by /proc/asound/timers, which faults on the\nstale ti->owner pointer.\n\nThe flag only has to be visible while the close is in progress, which is\nall its other users need.  Clear it in remove_slave_links(), under the\nsame timer->lock that sets it, once the instance is off every list.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/0c561fab50991df10b1e4daca25886c34a2a9c07","https://git.kernel.org/stable/c/a26a2e52736f9e39843ca66a2e1ce6bf1adbcd1e","https://git.kernel.org/stable/c/bb016091010ec401a06e6bdace0cd944ee03d371","https://git.kernel.org/stable/c/c2744d5f3aea474513fd2298daecb94a952ce441"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:49:10.689564601+00:00"},"epss":{"cve":"CVE-2026-74503","score":0.00175,"percentile":0.06963,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}