CVE-2022-48951

What it actually does

The bounds checks in snd_soc_put_volsw_sx() are only applied to the first channel, allowing out-of-bounds values to be written to the second channel in stereo controls.

Why it matters to the business

Potential audio subsystem instability or crashes on affected Linux systems could disrupt operations for devices relying on ALSA SoC sound controls, with moderate urgency due to low EPSS and no KEV listing despite mentions in broad 2024 exploitation campaigns.

How an attack unfolds

An attacker supplies crafted stereo volume control values that bypass first-channel-only bounds checks in snd_soc_put_volsw_sx(), writing out-of-bounds data to the second channel; context from listed threat actors indicates possible use in espionage or financially motivated Linux kernel campaigns.

How to fix it

Update to the fixed commit 7620d220e48563938d869da7689b8ac3f7721490 in librenms/librenms (GIT) or equivalent kernel patches that add bounds checks for the second channel.

How to confirm the fix worked

Confirm the presence of the bounds check addition for the second channel in snd_soc_put_volsw_sx() after applying the listed commit or patch; test stereo control operations to ensure no out-of-bounds writes occur.

Typical attack path

1. Identify a system using an unpatched Linux kernel with ALSA SoC stereo controls
2. Trigger snd_soc_put_volsw_sx() via userspace audio APIs or drivers with out-of-bounds values for the second channel
3. Achieve memory corruption leading to instability or further exploitation

How to detect it

Review kernel logs and audio subsystem traces for unexpected out-of-bounds behavior or crashes in snd_soc_put_volsw_sx(); correlate with threat actor mentions of Linux kernel out-of-bounds writes.

What your security team should do

• Prioritize patching Linux kernel audio subsystems to the fixed version within standard maintenance windows given low EPSS
• Monitor for any new EPSS increases or KEV inclusion
• Review audio driver usage in high-value assets for exposure