CVE-2026-93393

Name	CVE-2026-93393
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1148331

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
mongo-c-driver (PTS)	bookworm	1.23.1-1+deb12u3	vulnerable
	trixie	1.30.4-1+deb13u3	vulnerable
	forky	2.5.5-1	fixed
	sid	2.5.6-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
mongo-c-driver	source	(unstable)	2.5.5-1	unimportant		1148331

Notes

https://jira.mongodb.org/browse/CDRIVER-6417
Fixed by: https://github.com/mongodb/mongo-c-driver/commit/5536089200aeb837f27f39465d89506eeff689e1 (2.5.4)
Fixed by: https://github.com/mongodb/mongo-c-driver/commit/01b1cf32fbe78044676c2fb163ba4f561a8d3ee3 (1.30.11)
Only an issue when built with the Windows platform TLS backend.