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CVE-2026-81527— NoSQL injection via unquoted constant GroupBy keys in LINQ pipeline translation

Quick assessment

Affected
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驱动中，LINQ 到聚合查询的转换层（包括聚合表达式和查询过滤器的转换）存在 NoSQL/表达式注入漏洞。当应用程序提供的值被嵌入到某些查询结构中时，这些值中包含的特殊元素在查询发送到数据库之前未被正确转义，导致值的部分内容可能被数据库解释为查询逻辑，而非数据。因此，能够向受影响的查询中提供值（即由应用程序整合进查询）的用户，可能会导致返回非预期的数据，或使查询结果发生改变。

CVSS 6.5 · Medium
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I. Basic Information for CVE-2026-81527

Vulnerability Information
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Vulnerability Title
NoSQL injection via unquoted constant GroupBy keys in LINQ pipeline translation
Source: CVE Program / CVE List V5
Vulnerability Description
A NoSQL/expression injection weakness exists in the LINQ-to-aggregation query translation layer of the MongoDB C# Driver, in both aggregation expression and query filter translation. When application-supplied values are embedded in certain query constructs, special elements contained within those values are not properly escaped before the resulting query is transmitted to the database, so portions of the value may be interpreted by the database as query logic rather than as data. A user able to supply values that an application incorporates into an affected query may thereby cause unintended data to be returned or query results to be altered.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
数据查询逻辑中特殊元素的不当中和
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
MongoDB C# Driver 2.14.0 ~ 3.11.1 -

II. Public POCs for CVE-2026-81527

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III. Intelligence Information for CVE-2026-81527

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Other References for CVE-2026-81527 (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-2026-81521 6.5 MEDIUM Cross-database write retargeting via unvalidated dotted database name in Client.BulkWrite
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 product: C# Driver
Same vendor: MongoDB
Same weakness: CWE-943

V. Comments for CVE-2026-81527

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