CVE-2026-93393: MongoDB C Driver

High severity, CVSS 8.1. EPSS: 0.5% chance of exploitation in the next 30 days.

A heap-based buffer overflow exists in the TLS transport layer of the MongoDB C Driver when built with the Windows platform TLS backend. A remote endpoint that the client connects to can cause the driver to write uncontrolled data outside the bounds of a heap allocation while processing incoming encrypted traffic after the TLS handshake completes. No authentication or user interaction is required, because the affected processing occurs before any application-level authentication completes. Triggering this issue may lead to memory corruption in the client process, disclosure of adjacent heap memory, or termination of the process.

Affected products

• MongoDB C Driver: from 1.10.0, before 1.30.11 (fixed in 1.30.11); from 2.2.0, before 2.5.4 (fixed in 2.5.4)

Published 2026-09-17. Last modified 2026-09-29.