CVE-2023-6176

What it actually does

Null pointer dereference in the Linux kernel scatterwalk cryptographic API triggered by a maliciously constructed packet under specific socket configurations, resulting in a kernel crash (denial of service) or potential privilege escalation.

Why it matters to the business

Local users on affected Linux systems can cause unplanned downtime through system crashes or potentially gain elevated privileges, disrupting operations and increasing security risk on servers and endpoints running vulnerable kernels.

How an attack unfolds

An authenticated local attacker crafts a malicious network packet and configures a socket in a specific way to invoke the flawed scatterwalk code path in the kernel crypto API, triggering the null pointer dereference that crashes the system or allows privilege escalation.

How to fix it

Update the Linux kernel to the fixed commit cfaa80c91f6f99b9342b6557f0f0e1143e434066 or apply the corresponding stable kernel patch that resolves the null pointer dereference in scatterwalk.

How to confirm the fix worked

Verify the running kernel contains commit cfaa80c91f6f99b9342b6557f0f0e1143e434066 or is built from a source tree after that commit; test that the specific socket configuration no longer triggers a crash or oops in the crypto scatterwalk path.

Typical attack path

1. Obtain local user access on a target Linux system
2. Construct a malicious packet with specific socket options targeting the crypto scatterwalk API
3. Trigger the kernel code path to dereference a null pointer
4. Achieve kernel crash (DoS) or attempt to leverage for privilege escalation

How to detect it

Review kernel logs (dmesg, /var/log/kern.log, journalctl) for null pointer dereference or oops messages involving scatterwalk or crypto API functions; look for unusual local processes creating sockets with non-standard configurations around the time of a crash.

What your security team should do

• Prioritize patching Linux kernel installations to the fixed commit cfaa80c91f6f99b9342b6557f0f0e1143e434066
• Restrict local user accounts and review socket creation privileges where possible
• Monitor kernel logs for scatterwalk-related oops or null pointer dereference messages
• Apply defense-in-depth measures such as mandatory access controls to limit local exploit impact