CVE-2026-53291

What it actually does

This is a Linux kernel driver reliability flaw in the ALSA HDA Conexant audio driver. During device probing, the driver calls snd_hda_jack_detect_enable_callback() but previously did not verify whether the call returned an error pointer. If callback registration fails, for example because of memory allocation failure, the driver can continue initialization with jack detection state missing or invalid. A later headphone/microphone jack event or related driver operation can then dereference or use uninitialized/invalid state, potentially causing a kernel crash. The practical impact is denial of service on systems using affected Conexant HDA audio hardware and vulnerable kernel builds.

Why it matters to the business

Successful exploitation can crash an affected Linux system, interrupting user workstations, embedded devices, kiosks, or appliances that rely on the affected audio driver. Because this is not listed in CISA KEV, has no known public exploit maturity in the provided data, and has a very low EPSS score, broad internet-scale exploitation is unlikely; however, organizations with fleets of Linux endpoints or embedded systems using Conexant HDA audio should still treat it as a stability and availability patching issue.

How an attack unfolds

An attacker would need access to a system running a vulnerable Linux kernel with the ALSA HDA Conexant driver active and matching audio hardware present. The attacker’s objective is to reach the driver state where jack detection callback registration fails during probe, such as under resource exhaustion or another failure condition. Because the vulnerable driver does not properly stop initialization after the failed registration, the system may continue operating with incomplete jack-detection state. The attacker, or a physical/event trigger, then causes a jack detection event or related audio driver path to execute. When the driver handles that event using invalid or uninitialized callback state, the kernel may crash, producing a local denial of service. There is no indication from the provided data that this is being exploited by named threat actors, ransomware campaigns, or public exploit kits.

How to fix it

Update the Linux kernel to a version that includes the ALSA HDA Conexant fix that checks the return value of snd_hda_jack_detect_enable_callback() with IS_ERR() and propagates failures with PTR_ERR(). If using a distribution kernel, apply the vendor-provided kernel security or stable update once available. If maintaining a custom kernel, backport the upstream patch for the hda/conexant driver. Where immediate patching is not possible, reduce exposure by disabling unused Conexant HDA audio hardware, blacklisting the affected driver if audio is not required, preventing untrusted local users from inducing resource exhaustion, and prioritizing reboot windows for systems where availability is important.

How to confirm the fix worked

Confirm the running kernel package or custom build includes the patched ALSA hda/conexant change. Validate that the installed kernel version matches the relevant distribution advisory or contains the backported fix in the source tree. On custom builds, inspect the Conexant HDA probe path and verify the return value from snd_hda_jack_detect_enable_callback() is checked with IS_ERR() and errors are returned via PTR_ERR(). After patching, reboot into the fixed kernel and verify with uname -a and package manager metadata. For exposure validation, check whether the snd_hda_codec_conexant module is loaded, whether Conexant HDA audio devices are present, and whether the system is running a vulnerable kernel build.

Typical attack path

1. Identify a Linux system using the affected ALSA HDA Conexant audio driver.
2. Trigger or wait for driver probe or reprobe while creating conditions that cause snd_hda_jack_detect_enable_callback() to fail, such as memory/resource pressure.
3. Allow the vulnerable probe path to continue despite the failed callback registration.
4. Trigger a headphone/microphone jack detection event or related audio path.
5. Cause the kernel to access invalid or uninitialized jack detection state, resulting in a crash or system instability.

How to detect it

To determine whether this was already exploited or triggered, review kernel logs, persistent journal data, crash dumps, and system reboot records for crashes involving the ALSA HDA Conexant driver, jack detection, or the snd_hda_jack_detect_enable_callback path. Relevant sources include dmesg output, /var/log/kern.log, /var/log/messages, journalctl -k, pstore, kdump/vmcore artifacts, abrt/apport crash records, and system uptime/reboot telemetry. Look for kernel oops, panic, general protection fault, NULL pointer dereference, use-after-invalid-pointer style traces, or call stacks referencing snd_hda_codec_conexant, hda_codec, cx_probe, or jack detection routines shortly before an unexpected reboot. Because this issue is a kernel crash condition rather than a web or network intrusion, there may be no remote network IOC. Correlate crashes with local resource exhaustion, audio device reprobe events, suspend/resume, module load/unload activity, or physical/headset jack events. No named threat actors or ransomware use are indicated in the provided data.

• snd_hda_codec_conexant
• snd_hda_jack_detect_enable_callback
• cx_probe
• ALSA: hda/conexant
• hda/conexant
• Conexant
• kernel BUG
• kernel panic
• Oops:
• general protection fault
• NULL pointer dereference
• unable to handle kernel paging request
• /var/log/kern.log
• /var/log/messages
• journalctl -k
• /sys/fs/pstore
• /var/crash
• vmcore
• dmesg

What your security team should do

• Inventory Linux systems using Conexant HDA audio hardware or the snd_hda_codec_conexant kernel module.
• Prioritize patching endpoints, embedded systems, kiosks, and appliances where an unexpected reboot or kernel panic would cause operational disruption.
• Apply vendor kernel updates or backport the upstream ALSA hda/conexant fix to custom kernels.
• If patching is delayed and audio is not required, disable or blacklist the affected Conexant HDA driver as a temporary mitigation.
• Monitor kernel logs for ALSA HDA Conexant errors, jack detection failures, kernel oops messages, and unexpected reboots.
• Because the vulnerability is not KEV-listed and has low EPSS, handle it through standard kernel maintenance unless affected systems are mission-critical or exposed to untrusted local users.