CVE-2026-53291: Linux Kernel ALSA HDA Conexant DoS Flaw

CVE-2026-53291 Overview

CVE-2026-53291 is a Linux kernel vulnerability in the Advanced Linux Sound Architecture (ALSA) hda/conexant driver. The flaw resides in the cx_probe() function, which ignores the return value of snd_hda_jack_detect_enable_callback(). That helper returns a pointer that must be validated with IS_ERR() because it can return an error pointer on failure conditions such as memory allocation failure.

When registration fails, the driver continues probing without a valid jack detection callback. Subsequent handling of jack events or dereferencing of the uninitialized structure can trigger a kernel crash. The upstream fix propagates the error through PTR_ERR() to the probe caller.

Critical Impact
Local conditions that cause callback registration failure can lead to a kernel crash (denial of service) on affected systems using Conexant HDA audio codecs.

Affected Products

Linux kernel — ALSA hda/conexant driver (sound/pci/hda/patch_conexant.c)
Distributions shipping vulnerable stable kernel branches prior to the referenced fix commits
Systems using Conexant High Definition Audio (HDA) codecs

Discovery Timeline

2026-06-26 - CVE-2026-53291 published to NVD
2026-06-30 - Last updated in NVD database

Technical Details for CVE-2026-53291

Vulnerability Analysis

The vulnerability is a missing error check on a kernel API that returns an encoded error pointer. In cx_probe(), the driver calls snd_hda_jack_detect_enable_callback() to register a callback for jack detection events on Conexant HDA codecs. The function returns a pointer, and on failure paths such as kzalloc() returning NULL, it returns an ERR_PTR() value rather than a valid object pointer.

By ignoring this return value, the probe routine treats a failed registration as success. No callback is attached, and the associated tracking structure remains uninitialized. When the audio subsystem later receives a jack unsol event or the driver accesses the expected structure, the kernel dereferences invalid memory. This manifests as a kernel oops or panic, resulting in denial of service on the affected host.

The fix adds an IS_ERR() check on the returned pointer and propagates the failure code via PTR_ERR() so cx_probe() returns an error to its caller instead of continuing in an inconsistent state.

Root Cause

The root cause is improper error handling of a kernel helper that uses the ERR_PTR/IS_ERR convention. The caller assumed a non-NULL return implied success, which is incorrect for functions that encode errors in pointer values. The bug pattern is a Null Pointer Dereference class defect triggered by an uninitialized structure path.

Attack Vector

An attacker requires local conditions on a system with a Conexant HDA codec. Triggering the failure path typically requires inducing memory pressure or another allocation failure during driver probe. Reaching the crash also requires an event that exercises the missing callback, such as a jack plug or unplug event. The result is a kernel crash rather than code execution or privilege escalation. See the kernel fix commit d68f753 for the corrected error handling in cx_probe().

Detection Methods for CVE-2026-53291

Indicators of Compromise

Kernel oops or panic entries in dmesg or /var/log/kern.log referencing patch_conexant, snd_hda_codec, or jack event handlers
Unexpected audio subsystem failures after suspend/resume or headphone plug events on Conexant-equipped hardware
probe failures for the snd_hda_intel module on systems with Conexant codecs after applying the fix

Detection Strategies

Inventory running kernel versions across the fleet and compare against the fixed stable branches referenced in the kernel.org stable commits
Monitor kernel ring buffer telemetry for oops signatures involving snd_hda_jack and patch_conexant symbols
Correlate audio-subsystem crash reports with hardware inventory data identifying Conexant HDA codecs

Monitoring Recommendations

Forward kernel facility syslog messages to a central logging or SIEM platform for panic and oops keyword alerting
Enable kernel crash dump collection with kdump to capture stack traces for post-incident analysis
Track kernel package versions through configuration management tooling to confirm patched builds are deployed

How to Mitigate CVE-2026-53291

Immediate Actions Required

Update the Linux kernel to a version containing the ALSA hda/conexant fix from your distribution vendor
Reboot affected systems after applying the updated kernel package to load the corrected driver
Identify hosts using Conexant HDA codecs via lspci and cat /proc/asound/cards and prioritize those systems for patching

Patch Information

The upstream fix has been merged into multiple stable branches. Reference commits include 1da5c73, 49c2c59, a2a33e8, b0e2333, d68f753, dd110cc, and f837c7b. Apply the kernel update provided by your distribution once it includes any of these commits.

Workarounds

Blacklist the snd_hda_codec_conexant module on systems where audio is not required by adding it to /etc/modprobe.d/ until the kernel patch is deployed
Avoid inducing memory pressure during boot on unpatched systems to reduce the likelihood of hitting the allocation failure path
Restrict local access on unpatched multi-user systems to limit exposure to conditions that could trigger the crash

bash

# Example: blacklist the Conexant HDA codec module as a temporary workaround
echo "blacklist snd_hda_codec_conexant" | sudo tee /etc/modprobe.d/blacklist-conexant.conf
sudo update-initramfs -u
# Reboot to apply
sudo reboot