CVE-2026-6691
High
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.
SeverityHigh
CVSS7.8
Exploit probability—
Product
Mongodb C Driver
PublishedMay 6, 2026
First seenMay 6, 2026
Weakness typeCWE-120CWE-120
How to fix
Update
- mongodb c_driver2.1.2 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mongodb c_driver | 2.1.0 ≤ v < 2.1.2 | 2.1.2 |
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