# CVE-2026-81529: Connection-option injection via unescaped settings in the canonical MongoDB URL builder

> CVE-2026-81529: Connection-option injection via unescaped settings in the canonical MongoDB URL builder. CVSS 7.1 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-81529
Last updated: 2026-09-29T19:16:22Z

- Published: 2026-08-27 18:32 UTC · Updated: 2026-09-29 19:16 UTC · Assigner: mongodb
- CVSS: 7.1 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N
- EPSS: 0.29%, 21th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-88

## Description

Improper neutralization of delimiters in connection-URL construction allows connection-option injection in the MongoDB C\# Driver. When an application passes untrusted text into the driver's connection-URL builder and round-trips the builder back into a client configuration, the untrusted text is serialized without neutralizing the URL/option delimiters and is then re-parsed as authoritative connection options. A low-privileged user of such an application can thereby introduce or suppress security-relevant connection settings.

## Affected vendors and products

- MongoDB: C\# Driver

## Tracked companies

- [MongoDB Atlas](https://rewindex.com/company/mongodb-atlas.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-81529)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-81529)
- [https://jira.mongodb.org/browse/CSHARP-6171](https://jira.mongodb.org/browse/CSHARP-6171)
- [https://www.nuget.org/packages/MongoDB.Driver/3.11.1](https://www.nuget.org/packages/MongoDB.Driver/3.11.1)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-81529 · Markdown: https://rewindex.com/cve/CVE-2026-81529.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-81529 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:12:27.533Z