CVE-2026-81527: medium-severity vulnerability in MongoDB C# Driver
NoSQL injection via unquoted constant GroupBy keys in LINQ pipeline translation
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.9epss 0.3%
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.
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
Affected products
MongoDB · C# DriverRelated CVEs — MongoDB C# Driver
In the same product, most dangerous first.
CVE-2026-114644HIGHMemory-exhaustion denial of service via unbounded symbol interning during BSON/JSON deserializationEPSS 0.5%CVE-2026-88025MEDIUMGridFS data disclosure and deletion via query-operator injection in file IDs in the MongoDB C# DriverEPSS 0.5%CVE-2026-114643MEDIUMDuplicate geometry fields via unvalidated GeoJSON extra membersEPSS 0.4%CVE-2026-114651MEDIUMCross-document data leak via malformed BSON array parsing in reused thread bufferEPSS 0.4%CVE-2026-88026HIGHRegular expression injection via unescaped characters in LINQ query translation in MongoDB C# DriverEPSS 0.4%CVE-2026-114654MEDIUMBSON output corruption via out-of-range binary subtype bypassing UUID and OldBinary guardsEPSS 0.3%