# CVE-2026-120954: Silent element-count truncation via 32-bit bit-length overflow in packed-bit vector views

> CVE-2026-120954: Silent element-count truncation via 32-bit bit-length overflow in packed-bit vector views. CVSS 3.7 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-120954
Last updated: 2026-11-03T20:18:12Z

- Published: 2026-11-03 18:45 UTC · Updated: 2026-11-03 20:18 UTC · Assigner: mongodb
- CVSS: 3.7 (CVSS 3.1) · Severity: Low · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
- EPSS: 0.23%, 14th percentile (scored 2026-11-04)
- CISA KEV: no
- CWE: CWE-190

## Description

A weakness in the BSON library's handling of a specialized binary vector data type allows an arithmetic wraparound when computing the number of elements described by an oversized attacker-supplied value. On builds where the platform word size is 32 bits, an application that parses untrusted BSON data can be made to process only a small fraction of the supplied elements while the operation reports success, producing results that disagree with byte-oriented accessors and with 64-bit builds of the same library. No authentication or user interaction is required beyond getting the application to parse the data. The impact is limited to data integrity; memory safety is not affected and no information is disclosed.

## 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-2026-120954)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-120954)
- [https://jira.mongodb.org/browse/CDRIVER-6420](https://jira.mongodb.org/browse/CDRIVER-6420)

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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-2026-120954 · Markdown: https://rewindex.com/cve/CVE-2026-120954.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-120954 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-11-05T15:28:17.333Z