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CVE-2026-81520— MongoDB Connector for BI Unbounded Authentication Negotiation Leading to Connection Exhaustion

Quick assessment

Affected
MongoDB BI Connector
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.

尚未完成身份验证的网络可达客户端，可以通过发起基于 SASL 的登录交换流程，然后拒绝完成该流程，从而无限期地保持一个 MongoDB Connector for BI 的身份验证会话处于开放状态。由于协商循环没有整体时间限制，且对客户端的读取操作也没有设置截止时间，每个此类会话都会持续占用一个工作线程、一个客户端连接槽位以及相关的后端数据库连接，直到进程重启。如果反复利用这一行为，可能会耗尽已配置的连接容量，从而阻止正常用户建立新的会话。

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1027.004 · Compile After Delivery
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I. Basic Information for CVE-2026-81520

Vulnerability Information
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Vulnerability Title
MongoDB Connector for BI Unbounded Authentication Negotiation Leading to Connection Exhaustion
Source: CVE Program / CVE List V5
Vulnerability Description
A network-reachable client that has not yet authenticated can hold a MongoDB Connector for BI authentication session open indefinitely by beginning a SASL-based login exchange and then declining to complete it. Because the negotiation loop had no overall time bound and the read from the client had no deadline, each such session retains a worker, a client connection slot, and its associated backend database connections until the process is restarted. Repeated use of this behavior can consume the configured connection capacity and prevent legitimate users from establishing new sessions.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
远程资源无超时同步访问
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
MongoDB BI Connector 0 ~ 2.14.31 -

II. Public POCs for CVE-2026-81520

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III. Intelligence Information for CVE-2026-81520

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Same Patch Batch · MongoDB · 2026-08-28 · 11 CVEs total

CVE-2026-81532 8.8 HIGH BI Connector ODBC Driver Improper Bounds Checking on Cursor Name Leading to Memory Corrupt
CVE-2026-77586 8.0 HIGH MongoDB Connector for BI Unescaped Object Names in Generated SHOW CREATE Output
CVE-2026-81490 7.7 HIGH MongoDB Connector for BI Improper Error Handling During Schema Sampling May Cause Loss of
CVE-2026-81517 7.5 HIGH MongoDB Connector for BI Improper Error Handling of Log Write Failures May Cause Loss of S
CVE-2026-81518 7.5 HIGH BI Connector Optional Client Certificate Verification Allows Unauthenticated Connections
CVE-2026-81533 7.1 HIGH MongoDB BI Connector ODBC Driver Memory-Safety Issue When Parsing Oversized LIMIT Values
CVE-2026-76798 6.3 MEDIUM MongoSQL Transition Readiness Tool Improper Output Encoding in Generated HTML Reports
CVE-2026-76797 6.3 MEDIUM MongoSQL Transition Readiness Tool Improper Neutralization of Formula Elements in Generate
CVE-2026-77184 5.2 MEDIUM MongoDB Connector for BI Incomplete Escaping of Stored Metadata in Generated SHOW CREATE O
CVE-2026-76794 4.6 MEDIUM MongoDB BI Connector Transition Readiness Report Improper HTML Encoding When Processing Da

IV. Related Vulnerabilities

Same product: BI Connector
Same vendor: MongoDB
Same weakness: CWE-1088

V. Comments for CVE-2026-81520

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