CVE-2026-6691— MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow
Quick assessment
Affected
MongoDB Inc. MongoDB C Driver
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
MongoDB C Driver是MongoDB开源的一个用于在C语言程序中连接和操作MongoDB数据库的客户端驱动库。 MongoDB C Driver存在安全漏洞，该漏洞源于Cyrus SASL集成在用户名规范化期间执行不安全的字符串复制，可能导致堆缓冲区溢出。
Possible ATT&CK Techniques 1 AI
T1190 · Exploit Public-Facing ApplicationAffected Version Matrix 1
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| MongoDB Inc. | MongoDB C Driver | 2.1.0≤ 2.1.2 |
affected |
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I. Basic Information for CVE-2026-6691
Vulnerability Information
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Vulnerability Title
MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未进行输入大小检查的缓冲区拷贝(传统缓冲区溢出)
Source: CVE Program / CVE List V5
Vulnerability Title
MongoDB C Driver 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MongoDB C Driver是MongoDB开源的一个用于在C语言程序中连接和操作MongoDB数据库的客户端驱动库。 MongoDB C Driver存在安全漏洞，该漏洞源于Cyrus SASL集成在用户名规范化期间执行不安全的字符串复制，可能导致堆缓冲区溢出。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| MongoDB Inc. | MongoDB C Driver | 2.1.0 ~ 2.1.2 | - |
|
II. Public POCs for CVE-2026-6691
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-6691 (1)
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