CVE-2026-6691

HIGH

MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow

Title source: cna

Description

The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.

References (1)

Core 1

Core References

https://jira.mongodb.org/browse/CDRIVER-6134

Scores

CVSS v3 7.8

EPSS 0.0013

EPSS Percentile 3.0%

Attack Vector LOCAL

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact total

Details

CWE

CWE-120

Status published

Products (1)

MongoDB Inc./MongoDB C Driver 2.1.0 - 2.1.2

Published May 06, 2026

Tracked Since May 06, 2026