PT-2026-37642 · Mongodb · Mongodb C Driver

Published 2026-04-29 · Updated 2026-05-06 · CVE-2026-6691

Positive Technologies (AI Summary)

CVSS v4.0

8.6

High

Base vector

AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Name of the Vulnerable Software and Affected Versions mongo-c-driver (affected versions not specified)

Description The Cyrus SASL integration in the MongoDB C Driver performs unsafe string copying during username canonicalization. This leads to a heap buffer overflow, which is a memory corruption issue where data exceeds the allocated buffer in the heap area. This can be triggered before any authentication or network traffic by providing untrusted input in the username of a MongoDB URI when using the authMechanism=GSSAPI parameter.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Buffer Overflow

Weakness Enumeration

CWE-120

Related Identifiers

CVE-2026-6691

Affected Products

Mongodb C Driver

References · 13

• https://nvd.nist.gov/vuln/detail/CVE-2026-6691 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-6691 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-6691 · Security Note
• https://security-tracker.debian.org/tracker/CVE-2026-6691 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-6691 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-6691 · Vendor Advisory
• https://github.com/mongodb/mongo-c-driver/commit/d9c26f49e75d3de746a690db9c81ff5b4f6e21b0 · Note
• https://github.com/mongodb/mongo-c-driver/commit/b4984965877d559862e225beba09cb4e9d4a56a6 · Note
• https://twitter.com/UpwindMDR/status/2052102457828704649 · Twitter Post
• https://twitter.com/CVEnew/status/2052086729285455964 · Twitter Post
• https://jira.mongodb.org/browse/CDRIVER-6134 · Note
• https://twitter.com/infoflowcloud/status/2052087590564602005 · Twitter Post
• https://t.me/CVEtracker/52865 · Telegram Post