CVE-2026-74388

/// Technical 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_pr

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References