# CVE-2026-88035: Heap buffer overflow via wrapped size check during SASL username canonicalization in MongoDB C Driver

> CVE-2026-88035: Heap buffer overflow via wrapped size check during SASL username canonicalization in MongoDB C Driver. CVSS 4.7 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-88035
Last updated: 2026-09-16T18:08:46Z

- Published: 2026-09-10 18:07 UTC · Updated: 2026-09-16 18:08 UTC · Assigner: mongodb
- CVSS: 4.7 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS: 0.10%, 1th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-190

## Description

A size check in the client-side authentication path of the MongoDB C Driver can wrap around, so an unusually large user-name value is accepted and copied past the end of a small buffer. A party able to set the driver's connection settings may cause the application that embeds the driver to terminate unexpectedly. Reaching this code requires a build in which the optional external SASL authentication backend is present and a connection configured to use it.

## 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-2026-88035)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-88035)
- [https://jira.mongodb.org/browse/CDRIVER-6416](https://jira.mongodb.org/browse/CDRIVER-6416)

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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-2026-88035 · Markdown: https://rewindex.com/cve/CVE-2026-88035.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-88035 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:15:45.136Z