CVE-2026-90220

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

ALSA: seq: Don't leak the extension cell pointer in the bounce payload

The bounce_error_event() embeds the failed event in the bounce payload

by pointing data.ext.ptr at it. When that event is a queued

variable-length event, its own data.ext.ptr holds the address of its

first extension cell, put there by snd_seq_event_dup(). The payload

goes out verbatim through snd_seq_expand_var_event(), so the address

reaches userspace.

That is the same address commit 705dd6dcbc0e ("ALSA: seq: Clear

variable event pointer on read") removed from the event header. The

read path still clears it there, just above the call that expands the

payload.

Embed a sanitised copy instead, treated exactly as snd_seq_read()

treats the header. A stack copy is enough because delivery is

synchronous and snd_seq_event_dup() copies before returning.

An unprivileged client reaches this by setting SNDRV_SEQ_FILTER_BOUNCE,

queueing a variable-leng

/// 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