CVE-2026-120954

Name	CVE-2026-120954
Description	A weakness in the BSON library's handling of a specialized binary vector data type allows an arithmetic wraparound when computing the number of elements described by an oversized attacker-supplied value. On builds where the platform word size is 32 bits, an application that parses untrusted BSON data can be made to process only a small fraction of the supplied elements while the operation reports success, producing results that disagree with byte-oriented accessors and with 64-bit builds of the same library. No authentication or user interaction is required beyond getting the application to parse the data. The impact is limited to data integrity; memory safety is not affected and no information is disclosed.
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	fixed
	trixie	1.30.4-1+deb13u3	fixed
	forky, sid	2.5.8-1	fixed

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

Package	Type	Release	Fixed Version
mongo-c-driver	source	bookworm	(not affected)
mongo-c-driver	source	trixie	(not affected)
mongo-c-driver	source	(unstable)	2.5.8-1

Notes

[trixie] - mongo-c-driver <not-affected> (Vulnerable code introduced later)
[bookworm] - mongo-c-driver <not-affected> (Vulnerable code introduced later)
https://jira.mongodb.org/browse/CDRIVER-6420
Introduced with: https://github.com/mongodb/mongo-c-driver/commit/1126b6ec8e2d6899157c93e00dfe97a90a656381 (2.0.0)
Fixed by: https://github.com/mongodb/mongo-c-driver/commit/38cfddcf6308b60160376be9e4967f32fa1be796 (2.5.8)