CVE-2026-68201
Received Received - Intake

Linux Kernel Use-After-Free in ALSA Timer

Vulnerability report for CVE-2026-68201, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: drain a slave's callback before its master detaches it snd_timer_close_locked() drains the closing instance's own in-flight callback (IFLG_CALLBACK) before freeing it, but not its slaves'. When a master instance is closed, remove_slave_links() clears each slave's ->timer; the slave's own close then reads timer == NULL and takes the branch that skips the drain entirely (snd_timer_stop_slave() also no-ops on a NULL timer). So a slave whose callback is still running when the master is closed is freed underneath the live callback, leading to use-after-free. Drain the slaves too before remove_slave_links() severs them. snd_timer_stop() has already taken this instance off the active list, so no new slave callback can be queued. Take the slaves off the ack list so a pending one can't fire either, then wait for any that is already in flight.

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Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a use-after-free vulnerability in the Linux kernel's ALSA timer subsystem. When a master timer instance is closed, it fails to properly drain its slave timers' callbacks before detaching them. This allows a slave timer's callback to continue running after the slave's memory has been freed, leading to potential memory corruption or arbitrary code execution.

Detection Guidance

This vulnerability is specific to the Linux kernel's ALSA timer subsystem and requires kernel-level inspection. Detection involves checking kernel logs for use-after-free errors or kernel crashes related to ALSA timer operations. Commands like dmesg | grep -i 'ALSA\|timer\|use-after-free' may help identify suspicious activity.

Impact Analysis

This vulnerability could allow an attacker with local access to execute arbitrary code, escalate privileges, or cause a denial of service by triggering the use-after-free condition. It primarily affects systems using the ALSA timer subsystem, which is common in Linux systems with audio functionality.

Mitigation Strategies

Apply the latest kernel update from your Linux distribution to patch the vulnerability. If immediate patching is not possible, consider disabling ALSA timer functionality if not required, or restrict access to audio devices to reduce attack surface.

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