What’s Vulnerable › Vulnerabilities
CVE-2026-6691: MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow
- Severity: high (CVSS 7.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.1% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-05-06 · updated 2026-10-26
- Weakness: CWE-120
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.
Affected products
- MongoDB C# Driver: from 2.1.0 before 2.1.2 — fixed in 2.1.2
How to fix
Upgrade to a fixed version: MongoDB C# Driver 2.1.2. Check the vendor advisory for mitigations.
References
Get alerted when CVE-2026-6691 or the next vulnerability affects your stack