CVE-2023-52616

What it actually does

Uninitialized fields in the mpi_ec_ctx structure lead to invalid pointer dereference on release during certain elliptic curve operations such as SM2 Za calculation, despite initial __GFP_ZERO allocation.

Why it matters to the business

Local denial-of-service crashes on Linux systems performing specific cryptographic operations, disrupting availability of services and potentially requiring reboots in affected environments with high kernel crypto usage.

How an attack unfolds

An attacker with local access triggers SM2 or similar mpi_ec operations that exercise the incompletely cleared structure; on release the dangling pointer is accessed, causing a kernel crash. The low EPSS and absence from KEV indicate limited in-the-wild exploitation despite the 942-day-old disclosure.

How to fix it

Upgrade the Linux kernel to the commit 0c3687822259a7628c85cd21a3445cbe3c367165 or later. For AlmaLinux 8 systems, update socat to version 1.7.4.1-1.el8. Reboot after kernel updates and verify the patch is active.

How to confirm the fix worked

Confirm the presence of commit 0c3687822259a7628c85cd21a3445cbe3c367165 in the kernel source tree or running kernel version string; test SM2 operations post-upgrade to ensure no crash occurs on mpi_ec_ctx release.

Typical attack path

1. Obtain local execution on a Linux system
2. Invoke cryptographic code paths that allocate and later release an mpi_ec_ctx for SM2 Za or equivalent
3. Trigger access to an uncleared pointer field during mpi_ec_ctx cleanup
4. Cause kernel panic or process termination

How to detect it

Search kernel logs and dmesg for oops/panic messages referencing mpi_ec_ctx, mpi_ec_init, or SM2 Za calculation; correlate with processes performing cryptographic operations around the time of the crash.

• mpi_ec_init
• mpi_ec_ctx
• Za value for SM2

What your security team should do

• Prioritize kernel updates on all systems performing elliptic-curve cryptography
• Apply the AlmaLinux socat update where applicable
• Monitor kernel logs for mpi-related oops entries until patches are deployed