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vuln-cve/data/2026/90xxx/CVE-2026-90207.json
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{
"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": [
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"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"
},
{
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"status": "unaffected",
"versionType": "semver"
},
{
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"lessThanOrEqual": "6.1.*",
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},
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},
{
"version": "6.12.110",
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
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},
{
"version": "6.18.52",
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
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},
{
"version": "7.2.6",
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
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},
{
"version": "7.3",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
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"negate": false,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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{
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"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"
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{
"url": "https://git.kernel.org/stable/c/210c193a9ef1312fab153948c6928e4cfaa1f03b"
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{
"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",
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}