{ "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": "2026-10-19T08:59:43.508Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:59:43.508Z" }, "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", "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" } ] } ] } ], "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" } } } }