# CVE-2026-81528

## Summary

- **CVE ID:** CVE-2026-81528
- **Severity:** MEDIUM
- **CVSS Score:** 5.4 (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)
- **CWE:** CWE-943
- **Published:** Aug 27, 2026
- **Last Modified:** Aug 28, 2026

## Description

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.

## Affected Products

- MongoDB — C# Driver (2.9.0)

## References

- [CNA](https://www.nuget.org/packages/MongoDB.Driver/3.11.1)
- [CNA](https://jira.mongodb.org/browse/CSHARP-6158)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.16%
- **EPSS Percentile:** 5.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._