CVE-2025-23134 ALSA: timer: Don't take register_mutex with copy_from/to_user()

What is CVE-2025-23134?

CVE-2025-23134 is a medium-severity vulnerability in Linux kernel, published on 16 Apr 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

ALSA: timer: Don't take register_mutex with copy_from/to_user()

The infamous mmap_lock taken in copy_from/to_user() can be often problematic when it's called inside another mutex, as they might lead to deadlocks.

In the case of ALSA timer code, the bad pattern is with guard(mutex)(&register_mutex) that covers copy_from/to_user() -- which was mistakenly introduced at converting to guard(), and it had been carefully worked around in the past.

This patch fixes those pieces simply by moving copy_from/to_user() out of the register mutex lock again.

Weakness: CWE-667

Which versions are affected by CVE-2025-23134?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2025-23134?

Apply the vendor's patch.

Is CVE-2025-23134 being exploited?

There is no known exploitation of CVE-2025-23134 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2025-23134, DEBIAN-CVE-2025-23134, GHSA-gxg5-6xg7-gc7q, UBUNTU-CVE-2025-23134.