CVE-2024-42098

What it actually does

The ECDH private key buffer is not fully zeroized before being overwritten with a new key, allowing remnants of previous key material to persist in memory if the new key is shorter than the previous one.

Why it matters to the business

Organizations using Linux kernel cryptographic functions for key exchange may face increased risk of sensitive key material leakage, potentially compromising encrypted communications and requiring patching to maintain cryptographic security across many systems.

How an attack unfolds

An attacker with the ability to observe or dump memory could potentially recover fragments of previous private keys used in ECDH operations if shorter keys were subsequently set or generated, especially in environments where the kernel crypto module is exercised repeatedly.

How to fix it

Update the Linux kernel to include commit 39173b04abda87872b43c331468a4a14f8f05ce8 or later in the stable git tree to ensure private_key is explicitly zeroized.

How to confirm the fix worked

Confirm the running kernel contains the referenced commit, review source for the zeroize call before key assignment, and test ECDH key operations with keys of differing lengths.

Typical attack path

1. Locate systems leveraging the Linux kernel ECDH implementation
2. Trigger repeated key setting or generation operations with varying key lengths
3. Access memory or process dumps to extract unzeroized key remnants
4. Use recovered fragments to weaken or recover ECDH session keys

How to detect it

Examine kernel memory dumps or process artifacts around ECDH usage for unexpected key material patterns; review logs from crypto subsystems for repeated key operations.

What your security team should do

• Apply the kernel update containing the fix across all affected systems
• Audit applications and services that invoke kernel ECDH functions
• Prioritize patching on high-value or internet-facing hosts first
• Monitor vendor advisories for related cryptographic kernel changes