# CVE-2026-106431: One-byte heap buffer overflow in BSON bulk document writer in MongoDB C Driver

> CVE-2026-106431: One-byte heap buffer overflow in BSON bulk document writer in MongoDB C Driver. CVSS 5.7 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-106431
Last updated: 2026-10-08T20:49:23Z

- Published: 2026-10-08 18:40 UTC · Updated: 2026-10-08 20:49 UTC · Assigner: mongodb
- CVSS: 5.7 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
- EPSS: 0.10%, 1th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-787

## Description

An off-by-one error in the BSON bulk document writer in the MongoDB C Driver can write one zero byte immediately past a heap allocation when a document ends at a specific buffer boundary. An actor who can influence the size of documents serialized by an embedding application can corrupt adjacent process memory or terminate the process. Reaching this issue requires the application to use the BSON bulk-writer API and produce a precise cumulative document size.

## 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-2026-106431)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-106431)
- [https://jira.mongodb.org/browse/CDRIVER-6418](https://jira.mongodb.org/browse/CDRIVER-6418)

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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-2026-106431 · Markdown: https://rewindex.com/cve/CVE-2026-106431.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-106431 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:13:18.614Z