CVE-2026-81528 MEDIUM

CVE-2026-81528: NoSQL injection via array replacement bypassing update shape validation in driver write path

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

CVSS base score

5.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality
Integrity

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

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