CVE-2026-6691

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.

CVSS v3 7.8 HIGH

7.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 1.8 / Impact : 5.9

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://jira.mongodb.org/browse/CDRIVER-6134	Patch Vendor Advisory Issue Tracking

Configurations

Configuration 1 (hide)

cpe:2.3:a:mongodb:c_driver:*:*:*:*:*:mongodb:*:*

History

No history.

Information

Published : 2026-05-06 16:16

Updated : 2026-06-18 17:18

NVD link : CVE-2026-6691

Mitre link : CVE-2026-6691

CVE.ORG link : CVE-2026-6691

JSON object : View

Products Affected

mongodb

c_driver

CWE

CWE-120

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CWE-787

Out-of-bounds Write

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