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CVE-2026-81521— Cross-database write retargeting via unvalidated dotted database name in Client.BulkWrite in the MongoDB Go Driver

Quick assessment

Affected
MongoDB GO 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 Go 驱动的客户端级别批量写操作可能会接受调用方提供的、包含保留分隔符（如 或 ）的数据库名称，且在未对其进行转义的情况下，直接使用该名称构建操作的目标命名空间。因此，如果应用程序将不可信输入作为数据库名称传入，该写操作可能会被导向与预期不同的数据库和集合。此问题仅影响 API。

CVSS 6.5 · Medium

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-81521

Vulnerability Information
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Vulnerability Title
Cross-database write retargeting via unvalidated dotted database name in Client.BulkWrite in the MongoDB Go Driver
Source: CVE Program / CVE List V5
Vulnerability Description
The MongoDB Go Driver's client-level bulk write operation may accept a caller-supplied database name containing a reserved separator character without escaping it before the name is used to build the target namespace for the operation. An application that passes untrusted input as a database name could therefore have the write directed at a database and collection other than the ones it intended. Only the Client.BulkWrite API is affected.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对资源描述符的控制不恰当(资源注入)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
MongoDB GO Driver 2.1.0 ~ 2.8.2 -

II. Public POCs for CVE-2026-81521

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III. Intelligence Information for CVE-2026-81521

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Vendor Pages for CVE-2026-81521 (1)

Other References for CVE-2026-81521 (1)

Same Patch Batch · MongoDB · 2026-08-27 · 12 CVEs total

CVE-2026-81522 8.1 HIGH Cross-tenant database retargeting via dot/NUL injection in namespace strings in the C++ Dr
CVE-2026-81525 8.1 HIGH Cross-tenant database retargeting via dot/NUL injection in namespace strings in the PHP Dr
CVE-2026-81529 7.1 HIGH Connection-option injection via unescaped settings in the canonical MongoDB URL builder
CVE-2026-81527 6.5 MEDIUM NoSQL injection via unquoted constant GroupBy keys in LINQ pipeline translation
CVE-2026-81526 6.5 MEDIUM Cross-database write redirection via unvalidated dotted database name in bulk write namesp
CVE-2026-75159 5.9 MEDIUM MongoDB BI Connector Improper Memory Handling During Failed Kerberos Authentication May Ca
CVE-2026-81530 5.6 MEDIUM KMS master key exposure via unredacted credential serialization in driver settings string
CVE-2026-81528 5.4 MEDIUM NoSQL injection via array replacement bypassing update shape validation in driver write pa
CVE-2026-81524 5.4 MEDIUM Cross-tenant database retargeting via dot/NUL injection in namespace strings in the C Driv
CVE-2026-75573 4.4 MEDIUM MongoDB Connector for BI mongodrdl Logs TLS Private-Key Password When Duplicate Options Ar
CVE-2026-81523 4.4 MEDIUM Cross-tenant database retargeting via dot/NUL injection in namespace strings in libmongocr

IV. Related Vulnerabilities

Same vendor: MongoDB
Same weakness: CWE-99

V. Comments for CVE-2026-81521

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