CVE-2026-81527 MEDIUM

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

Vendor Mongodb
Product C# Driver
Weakness CWE-943
Published August 27, 2026
Last update August 28, 2026

CVSS base score

6.9/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

August 27, 2026 CVE published
August 28, 2026 Record updated