CVE-2026-6691
MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow
CVSS Score
7.8
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-120 |
| Vendor | mongodb inc. |
| Product | mongodb c driver |
| Published | May 6, 2026 |
| Last Updated | May 6, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
MongoDB Inc. / MongoDB C Driver
2.1.0 ≤ 2.1.2