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VulnerabilityPublished Updated

CVE-2026-74388: Linux kernel · ALSA: seq: oss: Fix UAF at handling events with embedded SysEx data

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in e96824274239ae4cd2f7b712644441cdc72c81a3 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in e96824274239ae4cd2f7b712644441cdc72c81a3, bc963e193b314f1441082e8b1ffe15eb255d0a44, 7c349b4f2a603202fb8c363bd2774a22ac2fddf3 +2
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < e96824274239ae4cd2f7b712644441cdc72c81a3
Fixed in
  • e96824274239ae4cd2f7b712644441cdc72c81a3
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < bc963e193b314f1441082e8b1ffe15eb255d0a44
Fixed in
  • bc963e193b314f1441082e8b1ffe15eb255d0a44
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 7c349b4f2a603202fb8c363bd2774a22ac2fddf3
Fixed in
  • 7c349b4f2a603202fb8c363bd2774a22ac2fddf3
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 7aad70cabd8f34cf11a9593fcd3f2ac3f5496943
Fixed in
  • 7aad70cabd8f34cf11a9593fcd3f2ac3f5496943
LinuxLinuxAffected
  • ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 6dc781778b595be94c31395b2cb167f65145d91f
Fixed in
  • 6dc781778b595be94c31395b2cb167f65145d91f
LinuxLinuxAffected
  • =2.6.12
Fixed in–

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 (?:?)

References

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