CVE-2026-81528: medium-severity vulnerability in MongoDB C# Driver
NoSQL injection via array replacement bypassing update shape validation in driver write path
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.3%
A MongoDB C# driver document-replacement code path omits the element-name/shape validation that the equivalent write paths apply, so a value supplied as a replacement is forwarded to the server without neutralization of query-language special elements. An application that passes untrusted, loosely-typed input as a replacement value therefore allows that input to be interpreted by the database as update logic rather than as data, executing under the application's own database credentials. Applications using strongly-typed document mappings are not affected.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/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%