{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90207","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.793Z","datePublished":"2026-09-17T16:07:22.825Z","dateUpdated":"2026-09-18T17:53:45.440Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-18T17:53:45.440Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: midi: Serialize input teardown with event_input\n\nsnd_midi_input_event() must not be running while a rawmidi substream is\nclosing, since this can lead to the trigger state becoming out-of-step\nthrough this sequence in snd_rawmidi_input_trigger():\n\n\tsnd_rawmidi_input_trigger(up=0)\n\t\t\t\t\tsnd_midi_input_event()\n\t\t\t\t\t -> snd_rawmidi_kernel_read()\n\t\t\t\t\t     -> snd_rawmidi_input_trigger(up=1)\n\t  -> cancel_work_sync()\n\nwhich ends with the underlying device being active unexpectedly.\n\nWhen this is called from close_substream(), further input can re-trigger\nthe input event leaving it running after rawmidi_release_priv() has set\nrfile->rmidi to NULL which leads to:\n\n\tUnable to handle kernel NULL pointer dereference at virtual address 00000000000000b0\n\tCall trace:\n\t snd_midi_input_event+0x3c/0x134 [snd_seq_midi] (P)\n\t snd_rawmidi_input_event_work+0x1c/0x2c\n\t process_one_work+0x150/0x3a4\n\t worker_thread+0x190/0x318\n\nApply a similar approach to commit ef7607ab1c8ad (\"ALSA: seq: midi:\nSerialize output teardown with event_input\") which fixed the same issue\nin the output direction, but updated to use RCU following Takashi Iwai's\nproposed follow-on patch [1].\n\nWith this change in place, midisynth_unsubscribe() clears the input file\nso snd_midi_input_event() will not re-trigger the stream and will be\nquiesced by the cancel_work_sync() in snd_rawmidi_input_trigger().\n\n[1] https://lore.kernel.org/linux-sound/20260813144224.753399-1-tiwai@suse.de/"}],"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 race is reached from a local sequencer client: snd_seq_open() on /dev/snd/seq, SNDRV_SEQ_IOCTL_SUBSCRIBE_PORT (midisynth_subscribe) to open the rawmidi input, then SNDRV_SEQ_IOCTL_UNSUBSCRIBE_PORT or client close (midisynth_unsubscribe -> snd_rawmidi_kernel_release). Bytes that schedule snd_midi_input_event come from the bound rawmidi device, not a network or radio protocol.\nAC:L - The attacker owns teardown (last unsubscribe/close) and starts input by subscribing: midisynth_subscribe sets runtime->event to snd_midi_input_event and snd_rawmidi_kernel_read() triggers the device. Concurrent snd_midi_input_event can re-call snd_rawmidi_input_trigger(up=1) during close_substream's trigger(up=0)/cancel_work_sync window. Repeating subscribe/unsubscribe on that live port makes the race retryable.\nPR:L - snd_seq_open() has no capable() check. check_subscription_permission() allows any sequencer client to subscribe to seq_midi ports because they advertise SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ. Typical DAC on /dev/snd/seq is audio-group/uaccess, so an unprivileged local user suffices; init-namespace root is not required.\nUI:N - The attacker opens their own /dev/snd/seq client, creates a destination port, issues SNDRV_SEQ_IOCTL_SUBSCRIBE_PORT to a seq_midi input port, and then unsubscribes or closes to run midisynth_unsubscribe. No other user must mount, click, or open a file.\nS:U - The UAF/NULL deref is in kernel rawmidi lifetime (close_substream/snd_rawmidi_runtime_free versus snd_rawmidi_input_event_work calling snd_midi_input_event). That is local kernel memory corruption in the same OS authority, not a VM, IOMMU, or sandbox escape.\nC:H - After cancel_work_sync, a re-triggered device can schedule runtime->event_work; close_substream then kfree()s snd_rawmidi_runtime while the work later does container_of() and calls runtime->event. Use-after-free of that heap object enables arbitrary reads via heap reuse of the freed runtime.\nI:H - The freed snd_rawmidi_runtime embeds event_work and the runtime->event function pointer that snd_rawmidi_input_event_work invokes. Heap spraying that object lets an attacker hijack the callback for arbitrary kernel write or control-flow hijack, not merely a one-shot crash.\nA:H - The reported crash is a NULL deref in snd_midi_input_event from snd_rawmidi_input_event_work after rawmidi_release_priv() nulls the file and close_substream frees runtime, which oopses the kernel and can be retried with subscribe/unsubscribe cycles."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["sound/core/seq/seq_midi.c"],"versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"de76a2b47582cd6dba2e15f024681bf377ecc94a","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"89d986897aff7275b42e075e556731b8353366af","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"6290afaae54c7a9fa3bca3b4d5433e6d83e8669d","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"210c193a9ef1312fab153948c6928e4cfaa1f03b","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"282a3ef9e4b63b2f6823bbbb3c1a90b002cdaf12","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"403f7f3ad3808a0096d84cf228fab68dc253fd9d","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["sound/core/seq/seq_midi.c"],"versions":[{"version":"2.6.12","status":"affected"},{"version":"0","lessThan":"2.6.12","status":"unaffected","versionType":"semver"},{"version":"6.1.188","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.157","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.110","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.52","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.6","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/de76a2b47582cd6dba2e15f024681bf377ecc94a"},{"url":"https://git.kernel.org/stable/c/89d986897aff7275b42e075e556731b8353366af"},{"url":"https://git.kernel.org/stable/c/6290afaae54c7a9fa3bca3b4d5433e6d83e8669d"},{"url":"https://git.kernel.org/stable/c/210c193a9ef1312fab153948c6928e4cfaa1f03b"},{"url":"https://git.kernel.org/stable/c/282a3ef9e4b63b2f6823bbbb3c1a90b002cdaf12"},{"url":"https://git.kernel.org/stable/c/403f7f3ad3808a0096d84cf228fab68dc253fd9d"}],"title":"ALSA: seq: midi: Serialize input teardown with event_input","x_generator":{"engine":"bippy-1.2.0"}}}}