CVE-2026-74388 - Vulnerability Details

Vendors	Products
Linux	Linux Kernel

Link	Providers
https://git.kernel.org/stable/c/6dc781778b595be94c31395b2cb167f65145d91f
https://git.kernel.org/stable/c/7aad70cabd8f34cf11a9593fcd3f2ac3f5496943
https://git.kernel.org/stable/c/7c349b4f2a603202fb8c363bd2774a22ac2fddf3

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: oss: Fix UAF at handling events with embedded SysEx data The OSS sequencer processes the input MIDI bytes into a sequencer event to be dispatched later (in snd_seq_oss_midi_putc() called from snd_seq_oss_process_event()). When it's a SysEx data, the event record contains data.ext.ptr pointer to the original SysEx bytes, and the referred data is copied into the pool afterwards at dispatching. The problem is that, if the sequencer port gets closed concurrently before the dispatch, the OSS sequencer core also releases the resources (in snd_seq_oss_midi_check_exit_port()), while the pending event may hold a stale pointer, eventually leading to a UAF at a later dispatch. Fortunately, there is already a refcounting mechanism (snd_use_lock_t) for the OSS MIDI device access, and for addressing the issue above, we just need to extend the refcount until the event gets dispatched. This patch extends snd_seq_oss_process_event() to give back the refcount object, which is in turn released after calling the sequencer dispatcher with the given event in the caller side. According to the original report, KASAN report as below: KASAN slab-use-after-free in snd_seq_event_dup+0x40c/0x470 RIP: 0033:0x7f2cb66a6340 Read of size 6 Call trace: dump_stack_lvl+0x73/0xb0 (?:?) print_report+0xd1/0x650 (?:?) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x1a7/0x340 (?:?) kasan_complete_mode_report_info+0x64/0x200 (?:?) kasan_report+0xf7/0x130 (?:?) snd_seq_event_dup+0x40c/0x470 (?:?) kasan_check_range+0x10c/0x1c0 (?:?) __asan_memcpy+0x27/0x70 (?:?) snd_seq_event_dup+0x9/0x470 (?:?) snd_seq_client_enqueue_event+0x139/0x240 (?:?) _raw_spin_unlock_irqrestore+0x4b/0x60 (?:?) snd_seq_kernel_client_enqueue+0x102/0x120 (?:?) snd_seq_oss_write+0x416/0x4e0 (?:?) apparmor_file_permission+0x20/0x30 (?:?) odev_write+0x3b/0x60 (?:?) vfs_write+0x1ce/0x850 (?:?) lock_release+0xc8/0x2a0 (?:?) __kasan_check_write+0x18/0x20 (?:?) __mutex_unlock_slowpath+0x129/0x510 (?:?) ksys_write+0xe1/0x180 (?:?) mutex_unlock+0x16/0x20 (?:?) odev_ioctl+0x65/0xc0 (?:?) __x64_sys_write+0x46/0x60 (?:?) x64_sys_call+0x7d/0x20d0 (?:?) do_syscall_64+0xc1/0x360 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)
Title		ALSA: seq: oss: Fix UAF at handling events with embedded SysEx data
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/6dc781778b595be94c31395b2cb167f65145d91f https://git.kernel.org/stable/c/7aad70cabd8f34cf11a9593fcd3f2ac3f5496943 https://git.kernel.org/stable/c/7c349b4f2a603202fb8c363bd2774a22ac2fddf3

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74388", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.891Z", "datePublished": "2026-08-15T05:59:03.147Z", "dateUpdated": "2026-08-15T05:59:03.147Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-15T05:59:03.147Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: oss: Fix UAF at handling events with embedded SysEx data\n\nThe OSS sequencer processes the input MIDI bytes into a sequencer\nevent to be dispatched later (in snd_seq_oss_midi_putc() called from\nsnd_seq_oss_process_event()). When it's a SysEx data, the event\nrecord contains data.ext.ptr pointer to the original SysEx bytes, and\nthe referred data is copied into the pool afterwards at dispatching.\nThe problem is that, if the sequencer port gets closed concurrently\nbefore the dispatch, the OSS sequencer core also releases the\nresources (in snd_seq_oss_midi_check_exit_port()), while the pending\nevent may hold a stale pointer, eventually leading to a UAF at a later\ndispatch.\n\nFortunately, there is already a refcounting mechanism (snd_use_lock_t)\nfor the OSS MIDI device access, and for addressing the issue above, we\njust need to extend the refcount until the event gets dispatched.\n\nThis patch extends snd_seq_oss_process_event() to give back the\nrefcount object, which is in turn released after calling the sequencer\ndispatcher with the given event in the caller side.\n\nAccording to the original report, KASAN report as below:\n\nKASAN slab-use-after-free in snd_seq_event_dup+0x40c/0x470\nRIP: 0033:0x7f2cb66a6340\nRead of size 6\nCall trace:\n dump_stack_lvl+0x73/0xb0 (?:?)\n print_report+0xd1/0x650 (?:?)\n srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n __virt_addr_valid+0x1a7/0x340 (?:?)\n kasan_complete_mode_report_info+0x64/0x200 (?:?)\n kasan_report+0xf7/0x130 (?:?)\n snd_seq_event_dup+0x40c/0x470 (?:?)\n kasan_check_range+0x10c/0x1c0 (?:?)\n __asan_memcpy+0x27/0x70 (?:?)\n snd_seq_event_dup+0x9/0x470 (?:?)\n snd_seq_client_enqueue_event+0x139/0x240 (?:?)\n _raw_spin_unlock_irqrestore+0x4b/0x60 (?:?)\n snd_seq_kernel_client_enqueue+0x102/0x120 (?:?)\n snd_seq_oss_write+0x416/0x4e0 (?:?)\n apparmor_file_permission+0x20/0x30 (?:?)\n odev_write+0x3b/0x60 (?:?)\n vfs_write+0x1ce/0x850 (?:?)\n lock_release+0xc8/0x2a0 (?:?)\n __kasan_check_write+0x18/0x20 (?:?)\n __mutex_unlock_slowpath+0x129/0x510 (?:?)\n ksys_write+0xe1/0x180 (?:?)\n mutex_unlock+0x16/0x20 (?:?)\n odev_ioctl+0x65/0xc0 (?:?)\n __x64_sys_write+0x46/0x60 (?:?)\n x64_sys_call+0x7d/0x20d0 (?:?)\n do_syscall_64+0xc1/0x360 (arch/x86/entry/syscall_64.c:87)\n entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["sound/core/seq/oss/seq_oss_event.c", "sound/core/seq/oss/seq_oss_event.h", "sound/core/seq/oss/seq_oss_ioctl.c", "sound/core/seq/oss/seq_oss_midi.c", "sound/core/seq/oss/seq_oss_midi.h", "sound/core/seq/oss/seq_oss_rw.c"], "versions": [{"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "6dc781778b595be94c31395b2cb167f65145d91f", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "7aad70cabd8f34cf11a9593fcd3f2ac3f5496943", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "7c349b4f2a603202fb8c363bd2774a22ac2fddf3", "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/oss/seq_oss_event.c", "sound/core/seq/oss/seq_oss_event.h", "sound/core/seq/oss/seq_oss_ioctl.c", "sound/core/seq/oss/seq_oss_midi.c", "sound/core/seq/oss/seq_oss_midi.h", "sound/core/seq/oss/seq_oss_rw.c"], "versions": [{"version": "2.6.12", "status": "affected"}, {"version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2-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": "6.18.40"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.1.5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.2-rc1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/6dc781778b595be94c31395b2cb167f65145d91f"}, {"url": "https://git.kernel.org/stable/c/7aad70cabd8f34cf11a9593fcd3f2ac3f5496943"}, {"url": "https://git.kernel.org/stable/c/7c349b4f2a603202fb8c363bd2774a22ac2fddf3"}], "title": "ALSA: seq: oss: Fix UAF at handling events with embedded SysEx data", "x_generator": {"engine": "bippy-1.2.0"}}}}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["sound/core/seq/oss/seq_oss_event.c", "sound/core/seq/oss/seq_oss_event.h", "sound/core/seq/oss/seq_oss_ioctl.c", "sound/core/seq/oss/seq_oss_midi.c", "sound/core/seq/oss/seq_oss_midi.h", "sound/core/seq/oss/seq_oss_rw.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "6dc781778b595be94c31395b2cb167f65145d91f", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "7aad70cabd8f34cf11a9593fcd3f2ac3f5496943", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "7c349b4f2a603202fb8c363bd2774a22ac2fddf3", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["sound/core/seq/oss/seq_oss_event.c", "sound/core/seq/oss/seq_oss_event.h", "sound/core/seq/oss/seq_oss_ioctl.c", "sound/core/seq/oss/seq_oss_midi.c", "sound/core/seq/oss/seq_oss_midi.h", "sound/core/seq/oss/seq_oss_rw.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "2.6.12"}, {"lessThan": "2.6.12", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.40", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.5", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2-rc1", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: oss: Fix UAF at handling events with embedded SysEx data\n\nThe OSS sequencer processes the input MIDI bytes into a sequencer\nevent to be dispatched later (in snd_seq_oss_midi_putc() called from\nsnd_seq_oss_process_event()). When it's a SysEx data, the event\nrecord contains data.ext.ptr pointer to the original SysEx bytes, and\nthe referred data is copied into the pool afterwards at dispatching.\nThe problem is that, if the sequencer port gets closed concurrently\nbefore the dispatch, the OSS sequencer core also releases the\nresources (in snd_seq_oss_midi_check_exit_port()), while the pending\nevent may hold a stale pointer, eventually leading to a UAF at a later\ndispatch.\n\nFortunately, there is already a refcounting mechanism (snd_use_lock_t)\nfor the OSS MIDI device access, and for addressing the issue above, we\njust need to extend the refcount until the event gets dispatched.\n\nThis patch extends snd_seq_oss_process_event() to give back the\nrefcount object, which is in turn released after calling the sequencer\ndispatcher with the given event in the caller side.\n\nAccording to the original report, KASAN report as below:\n\nKASAN slab-use-after-free in snd_seq_event_dup+0x40c/0x470\nRIP: 0033:0x7f2cb66a6340\nRead of size 6\nCall trace:\n dump_stack_lvl+0x73/0xb0 (?:?)\n print_report+0xd1/0x650 (?:?)\n srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n __virt_addr_valid+0x1a7/0x340 (?:?)\n kasan_complete_mode_report_info+0x64/0x200 (?:?)\n kasan_report+0xf7/0x130 (?:?)\n snd_seq_event_dup+0x40c/0x470 (?:?)\n kasan_check_range+0x10c/0x1c0 (?:?)\n __asan_memcpy+0x27/0x70 (?:?)\n snd_seq_event_dup+0x9/0x470 (?:?)\n snd_seq_client_enqueue_event+0x139/0x240 (?:?)\n _raw_spin_unlock_irqrestore+0x4b/0x60 (?:?)\n snd_seq_kernel_client_enqueue+0x102/0x120 (?:?)\n snd_seq_oss_write+0x416/0x4e0 (?:?)\n apparmor_file_permission+0x20/0x30 (?:?)\n odev_write+0x3b/0x60 (?:?)\n vfs_write+0x1ce/0x850 (?:?)\n lock_release+0xc8/0x2a0 (?:?)\n __kasan_check_write+0x18/0x20 (?:?)\n __mutex_unlock_slowpath+0x129/0x510 (?:?)\n ksys_write+0xe1/0x180 (?:?)\n mutex_unlock+0x16/0x20 (?:?)\n odev_ioctl+0x65/0xc0 (?:?)\n __x64_sys_write+0x46/0x60 (?:?)\n x64_sys_call+0x7d/0x20d0 (?:?)\n do_syscall_64+0xc1/0x360 (arch/x86/entry/syscall_64.c:87)\n entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)"}], "id": "CVE-2026-74388", "lastModified": "2026-08-15T06:22:40.733", "metrics": {}, "published": "2026-08-15T06:22:40.733", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6dc781778b595be94c31395b2cb167f65145d91f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7aad70cabd8f34cf11a9593fcd3f2ac3f5496943"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7c349b4f2a603202fb8c363bd2774a22ac2fddf3"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

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