{"id":"CVE-2026-74503","title":"ALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes","summary":"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…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 586b219a22b1032b28b8bd356b963276c5e5bf53 < bb016091010ec401a06e6bdace0cd944ee03d371","Linux >= f46093dd22969037beb1fce2e043f3236be41c92 < a26a2e52736f9e39843ca66a2e1ce6bf1adbcd1e","Linux >= da3039e91d1f835874ed6e9a33ea19ee80c2cb92 < 0c561fab50991df10b1e4daca25886c34a2a9c07","Linux >= da3039e91d1f835874ed6e9a33ea19ee80c2cb92 < c2744d5f3aea474513fd2298daecb94a952ce441","Linux 60e73ab87b84bbd6bd7ddd1d16019a3a3705ab8f","Linux >= 6.12.94 < 6.12.103","Linux >= 6.18.36 < 6.18.44","Linux >= 7.0.13 < 7.1","Linux 7.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T18:58:23.278795Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:05:50.728Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74503","references":[{"url":"https://git.kernel.org/stable/c/bb016091010ec401a06e6bdace0cd944ee03d371"},{"url":"https://git.kernel.org/stable/c/a26a2e52736f9e39843ca66a2e1ce6bf1adbcd1e"},{"url":"https://git.kernel.org/stable/c/0c561fab50991df10b1e4daca25886c34a2a9c07"},{"url":"https://git.kernel.org/stable/c/c2744d5f3aea474513fd2298daecb94a952ce441"}],"tags":["cve.org"],"epss":0.00175,"epssPercentile":0.06541,"ingestedAt":"2026-10-16T19:46:24.354Z","slug":"CVE-2026-74503","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 586b219a22b1032b28b8bd356b963276c5e5bf53 < bb016091010ec401a06e6bdace0cd944ee03d371`\n- `Linux >= f46093dd22969037beb1fce2e043f3236be41c92 < a26a2e52736f9e39843ca66a2e1ce6bf1adbcd1e`\n- `Linux >= da3039e91d1f835874ed6e9a33ea19ee80c2cb92 < 0c561fab50991df10b1e4daca25886c34a2a9c07`\n- `Linux >= da3039e91d1f835874ed6e9a33ea19ee80c2cb92 < c2744d5f3aea474513fd2298daecb94a952ce441`\n- `Linux 60e73ab87b84bbd6bd7ddd1d16019a3a3705ab8f`\n- `Linux >= 6.12.94 < 6.12.103`\n- `Linux >= 6.18.36 < 6.18.44`\n- `Linux >= 7.0.13 < 7.1`\n- `Linux 7.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}