---
cve: "CVE-2026-6691"
severity: "HIGH"
cvss: 8.6
epss: "0.1%"
vendor: "MongoDB Inc."
kev: false
exploited: false
published: "2026-05-06 16:16:11"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-21T01:28:52+02:00"
---

# CVE-2026-6691

> 8.6 HIGH

## Beschreibung

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-Vektor

```
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 81c27ddadd54e80d9743dee0e8b7a0a862aa6ab5 (Commit)

## Referenzen

- <https://jira.mongodb.org/browse/CDRIVER-6134>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-6691) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_