Vulnerability · Published Aug 27, 2026 · Assigned by mongodb
CVE-2026-81527NoSQL injection via unquoted constant GroupBy keys in LINQ pipeline translation
Medium 6.5
In plain English
A medium-severity security flaw in C# Driver from MongoDB. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).
Official 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.
Affected products (as reported)
Weakness: CWE-943 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N