{"id":"CVE-2026-68202","state":"PUBLISHED","title":"ALSA: seq: close a re-opened queue timer in the destructor","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: close a re-opened queue timer in the destructor\n\nqueue_delete() closes the queue timer, then frees it. snd_seq_timer_close()\nclears q->timer->timeri. snd_use_lock_sync() then drains borrowers, and\nsnd_seq_timer_delete() frees q->timer.\n\nA borrower can re-open the timer inside that window. A SET_QUEUE_CLIENT\nthat took a queueptr() use_lock reference before the queue was unlinked\nruns snd_seq_timer_open() after the close. Open refuses re-open only while\ntimeri is set, and the close just cleared it, so it re-opens timeri.\n\nsnd_seq_timer_delete() does not close that instance. Its snd_seq_timer_stop()\nis a no-op, because running was cleared first. So it frees q->timer with the\ninstance still live. The queue is freed next.\n\nThe instance stays on the global timer with callback_data pointing at the\nfreed queue. A non-owner START on the unlocked queue arms it. The next tick\nderefs the freed queue in snd_seq_timer_interrupt().\n\nReachable by an unprivileged user with access to /dev/snd/seq. No CAP and\nno queue ownership required.\n\nClose any lingering instance in the destructor. There, ->timeri can no\nlonger change: the queue is unlinked and all use_lock borrowers have\ndrained, so no snd_seq_queue_use() can re-open it. Close it before clearing\nq->timer. snd_timer_close() waits for any in-flight snd_seq_timer_interrupt()\nto finish, and that callback still reads q->timer (via snd_seq_check_queue()),\nso q->timer must stay valid until it drains.","publishedAt":"2026-08-10T12:00:21.279Z","updatedAt":"2026-10-19T20:58:57.086Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b7feeaca1f53b10df9b4de9eaf611767ca70dc92","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"7478ef94b49bc9789cf1a003deec58b42283dde4","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"9d9be6fc30f384f92c4e1b8ed40bd9d4796b7833","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"fb40d03ed792a8a8bf77aa0ee15df57b0ff78b07","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"24f0cabf173539f048946c8fc221131dc221f277","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"6a10025c7fd09a7d2af37a3ae1da188569fce470","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"31a6163e301d832060f8236f1ed17cbc1ca198df","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2c4dc0ed50b05cd847a4b34b8cebf0775f19aeb9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["sound/core/seq/seq_timer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.10.266","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.217","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["sound/core/seq/seq_timer.c"]}],"references":["https://git.kernel.org/stable/c/b7feeaca1f53b10df9b4de9eaf611767ca70dc92","https://git.kernel.org/stable/c/7478ef94b49bc9789cf1a003deec58b42283dde4","https://git.kernel.org/stable/c/9d9be6fc30f384f92c4e1b8ed40bd9d4796b7833","https://git.kernel.org/stable/c/fb40d03ed792a8a8bf77aa0ee15df57b0ff78b07","https://git.kernel.org/stable/c/24f0cabf173539f048946c8fc221131dc221f277","https://git.kernel.org/stable/c/6a10025c7fd09a7d2af37a3ae1da188569fce470","https://git.kernel.org/stable/c/31a6163e301d832060f8236f1ed17cbc1ca198df","https://git.kernel.org/stable/c/2c4dc0ed50b05cd847a4b34b8cebf0775f19aeb9"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/68xxx/CVE-2026-68202.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-68202","state":"PUBLISHED","datePublished":"2026-08-10T12:00:21.279Z","dateUpdated":"2026-10-19T20:58:57.086Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-30T09:28:09.374Z"},"containers":{"cna":{"title":"ALSA: seq: close a re-opened queue timer in the destructor","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: close a re-opened queue timer in the destructor\n\nqueue_delete() closes the queue timer, then frees it. snd_seq_timer_close()\nclears q->timer->timeri. snd_use_lock_sync() then drains borrowers, and\nsnd_seq_timer_delete() frees q->timer.\n\nA borrower can re-open the timer inside that window. A SET_QUEUE_CLIENT\nthat took a queueptr() use_lock reference before the queue was unlinked\nruns snd_seq_timer_open() after the close. Open refuses re-open only while\ntimeri is set, and the close just cleared it, so it re-opens timeri.\n\nsnd_seq_timer_delete() does not close that instance. Its snd_seq_timer_stop()\nis a no-op, because running was cleared first. So it frees q->timer with the\ninstance still live. The queue is freed next.\n\nThe instance stays on the global timer with callback_data pointing at the\nfreed queue. A non-owner START on the unlocked queue arms it. The next tick\nderefs the freed queue in snd_seq_timer_interrupt().\n\nReachable by an unprivileged user with access to /dev/snd/seq. No CAP and\nno queue ownership required.\n\nClose any lingering instance in the destructor. There, ->timeri can no\nlonger change: the queue is unlinked and all use_lock borrowers have\ndrained, so no snd_seq_queue_use() can re-open it. Close it before clearing\nq->timer. snd_timer_close() waits for any in-flight snd_seq_timer_interrupt()\nto finish, and that callback still reads q->timer (via snd_seq_check_queue()),\nso q->timer must stay valid until it drains."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b7feeaca1f53b10df9b4de9eaf611767ca70dc92","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"7478ef94b49bc9789cf1a003deec58b42283dde4","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"9d9be6fc30f384f92c4e1b8ed40bd9d4796b7833","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"fb40d03ed792a8a8bf77aa0ee15df57b0ff78b07","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"24f0cabf173539f048946c8fc221131dc221f277","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"6a10025c7fd09a7d2af37a3ae1da188569fce470","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"31a6163e301d832060f8236f1ed17cbc1ca198df","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2c4dc0ed50b05cd847a4b34b8cebf0775f19aeb9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["sound/core/seq/seq_timer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.10.266","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.217","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["sound/core/seq/seq_timer.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/b7feeaca1f53b10df9b4de9eaf611767ca70dc92"},{"url":"https://git.kernel.org/stable/c/7478ef94b49bc9789cf1a003deec58b42283dde4"},{"url":"https://git.kernel.org/stable/c/9d9be6fc30f384f92c4e1b8ed40bd9d4796b7833"},{"url":"https://git.kernel.org/stable/c/fb40d03ed792a8a8bf77aa0ee15df57b0ff78b07"},{"url":"https://git.kernel.org/stable/c/24f0cabf173539f048946c8fc221131dc221f277"},{"url":"https://git.kernel.org/stable/c/6a10025c7fd09a7d2af37a3ae1da188569fce470"},{"url":"https://git.kernel.org/stable/c/31a6163e301d832060f8236f1ed17cbc1ca198df"},{"url":"https://git.kernel.org/stable/c/2c4dc0ed50b05cd847a4b34b8cebf0775f19aeb9"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached through ioctls on the local character device /dev/snd/seq (SNDRV_SEQ_IOCTL_CREATE_QUEUE/DELETE_QUEUE/SET_QUEUE_CLIENT); no network or adjacent-network path exists to the ALSA sequencer.\nAC:L - The attacker controls both sides of the race — one thread deletes the queue while another spins on SET_QUEUE_CLIENT holding a queueptr() reference — and can retry the loop indefinitely on a default kernel with CONFIG_SND_SEQUENCER, so the window is reliably hit.\nPR:L - Only an unprivileged local user able to open /dev/snd/seq is needed; snd_seq_queue_use() performs no owner or access check and no capability is required, as the fix commit states explicitly.\nUI:N - The attacker's own threads create, delete and re-use the queue and the global system timer fires on its own; no victim action is involved.\nS:U - The use-after-free corrupts kernel heap objects within the same kernel security authority, giving at most kernel privilege escalation rather than crossing a VM, IOMMU or sandbox boundary.\nC:H - The stale timer instance dereferences the freed snd_seq_queue and snd_seq_timer, reading tick/time fields and freed prioq pointers that can be reclaimed by attacker-sprayed objects, giving a route to disclose arbitrary kernel memory.\nI:H - snd_seq_timer_interrupt() writes cur_time, tick and last_update into the freed snd_seq_timer slab and snd_seq_check_queue() dispatches events through freed queue pointers, yielding a controllable write primitive on reclaimed heap memory suitable for privilege escalation.\nA:H - Even unexploited, the timer callback derefs freed memory and takes a spinlock in a freed object from interrupt context, causing oops, lock corruption or panic — a repeatable denial of service for any local user."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-23T12:46:08.116Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.10.266"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.15.217"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.148"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.101"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-68202","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:45:51.106270Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","lang":"en","type":"CWE","description":"CWE-416 Use After Free"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:58:57.086Z"}}]}}}