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 driver是美国MongoDB公司开源的一个数据库连接驱动。 MongoDB go driver 2.1.0版本至2.8.2之前版本存在输入验证错误漏洞，该漏洞源于客户端级批量写操作在构建目标命名空间前未对包含保留分隔符的调用者提供的数据库名称进行转义，可能导致写入被定向到非预期的数据库和集合。
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
Vulnerability Title
MongoDB go driver 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MongoDB go driver是美国MongoDB公司开源的一个数据库连接驱动。 MongoDB go driver 2.1.0版本至2.8.2之前版本存在输入验证错误漏洞，该漏洞源于客户端级批量写操作在构建目标命名空间前未对包含保留分隔符的调用者提供的数据库名称进行转义，可能导致写入被定向到非预期的数据库和集合。
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
II. Public POCs for CVE-2026-81521
| # | POC Description | Source Link | Shenlong Link |
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Vendor Pages for CVE-2026-81521 (2)
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
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CVE-2026-104005
Incorrect authorization in MongoDB Server router for bulk wr -
CVE-2026-104004
Collection validators using collation-accepting expressions -
CVE-2026-103965
Fixed values in MongoDB Server $bucket stage may be misread -
CVE-2026-96299
Missing Authorization Check on Internal Aggregation Stage in -
CVE-2026-96297
MongoDB Server may disclose process memory via a crafted `$_
Same weakness: CWE-99
V. Comments for CVE-2026-81521
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