CVE-2026-53192
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk3th percentile — higher than 3% of all known CVEs
Summary
A use-after-free (UAF) vulnerability was found in the snd_timer_user_params() function of the ALSA driver in the Linux kernel. The issue occurs when a user timer (CONFIG_SND_UTIMER) is being closed while another thread concurrently executes the SNDRV_TIMER_IOCTL_PARAMS ioctl, which was not protected by the register_mutex. The patch adds the missing synchronization to prevent the race condition.
Risk Assessment
A local attacker could exploit this vulnerability to gain unauthorized access to kernel memory, potentially leading to privilege escalation or denial of service (DoS).
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit 5a4c6f7e8b9c). If updating is not possible, restrict access to the ALSA timer interface for untrusted users.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Fix UAF at snd_timer_user_params() At releasing a timer object, e.g. when a userspace timer (CONFIG_SND_UTIMER) gets closed and snd_timer_free() is called, it tries to detach the timer instances and release the resources. However, it's still possible that other in-flight tasks are holding the timer instance where the to-be-deleted timer object is associated, and this may lead to racy accesses. Fortunately, most of ioctls dealing with the timer instance list already have the protection with register_mutex, and this also avoids such races. But, SNDRV_TIMER_IOCTL_PARAMS isn't protected, hence the concurrent ioctl may lead to use-after-free. This patch just adds the guard with register_mutex to protect snd_timer_user_params() for covering the code path as a quick workaround. It's no hot-path but rather a rarely issued ioctl, so the performance penalty doesn't matter.