CVE Catalog

CVE-2026-74278

Low risk· EPSS 6%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.17%

6th percentile - higher than 6% of all known CVEs

Summary

A vulnerability in the Linux kernel ALSA SEQ subsystem leaks a kernel heap address to userspace. The bounce_error_event() function sent SNDRV_SEQ_EVENT_KERNEL_ERROR with a raw pointer to all clients, including user clients, exposing the address via copy_to_user(). The issue affects the fixed-length branch not covered by a previous fix.

Risk Assessment

The kernel heap address leak can help an attacker bypass security mechanisms (e.g., ASLR) and facilitate further kernel attacks. This information disclosure is a stepping stone for privilege escalation or local exploitation.

Recommendation

Update the Linux kernel to a patched version addressing CVE-2026-74278 immediately. If not possible, restrict access to the ALSA SEQ interface to trusted processes only.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Fix kernel heap address leak in bounce_error_event() The comment above bounce_error_event() documents that user clients should receive SNDRV_SEQ_EVENT_BOUNCE with the original event embedded as variable-length data, while kernel clients should receive SNDRV_SEQ_EVENT_KERNEL_ERROR with a quoted kernel pointer. However, the implementation unconditionally uses SNDRV_SEQ_EVENT_KERNEL_ERROR with data.quote.event set to the raw struct snd_seq_event pointer for all clients. When a bounce error event is delivered to a USER_CLIENT via snd_seq_read(), the kernel heap address in data.quote.event is exposed to userspace through copy_to_user() in the fixed-length branch. This is a distinct leak path from the one addressed by commit 705dd6dcbc0e ("ALSA: seq: Clear variable event pointer on read"), which sanitizes data.ext.ptr in the variable-length branch of snd_seq_read(). The bounce_error_event() leak uses fixed-length events that take the else branch where no sanitization occurs. Differentiate the bounce event by client type. For USER_CLIENT, send SNDRV_SEQ_EVENT_BOUNCE with SNDRV_SEQ_EVENT_LENGTH_VARIABLE and data.ext pointing to the original event. The variable-length path in snd_seq_event_dup() copies the event data into chained cells, and snd_seq_expand_var_event() copies only the content -- never the pointer -- to userspace. For KERNEL_CLIENT, keep the existing SNDRV_SEQ_EVENT_KERNEL_ERROR behavior with the quoted pointer.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS