CVE-2026-93394

Name	CVE-2026-93394
Description	A flaw in libmongoc's SCRAM authentication implementation caused the client to continue the authentication handshake and transmit the client proof even when a nonce mismatch was detected in the server's first message. An unauthorized party with a man-in-the-middle position could exploit this by injecting a crafted server-first-message containing a controlled salt and low iteration count, then capturing the resulting client proof to perform offline password cracking. This vulnerability is mitigated by TLS, which is standard in production deployments.
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)

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, sid	2.5.3-1	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)	2.4.0-1

Notes

https://jira.mongodb.org/browse/CDRIVER-6315
Fixed by: https://github.com/mongodb/mongo-c-driver/commit/6b27da3e0384170ac0efc75321556bd37a2ae03f (2.4.0)
Fixed by: https://github.com/mongodb/mongo-c-driver/commit/0b9bbbff0b949dcddb97e518e7fdb5950e187be3 (1.30.11)