# CVE-2026-84966: mongo-cxx-driver: An incorrect numeric type conversion in the BSON document building component of the MongoDB C++ Driver may cause a le...

CVE-2026-84966 is fixed in mongo-cxx-driver on 1 platform by DEBIAN-CVE-2026-84966 (version 4.5.2-1), released September 10, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-84966
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0014
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 3, 2026

## Description

An incorrect numeric type conversion in the BSON document building component of the MongoDB C++ Driver may cause a length value to be interpreted incorrectly. When an application supplies an extremely large, non-terminated field name to the builder, the library may read memory outside the intended buffer and terminate the calling process. No authentication is required, but the calling application must pass the oversized name in a specific form.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | mongo-cxx-driver Debian 14 | 4.5.2-1 | [DEBIAN-CVE-2026-84966](https://patchblox.com/security/data/fix/linux/debian-cve-2026-84966.md) | Sep 10, 2026 |

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Data as of 2026-11-09T13:31:49Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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