# CVE-2026-114646: NoSQL command injection via mismatched raw BSON length prefix written verbatim to the wire

Status: published. Published: 2026-10-22. Updated: 2026-11-02.

A data-validation flaw exists in the BSON handling and binary serialization path of the MongoDB C# Driver. When an application constructs a raw or lazy BSON document object from externally supplied binary data, the driver does not verify that the size quantity declared inside that data matches the amount of data actually provided, and it copies the data onto the wire unchanged. An unauthenticated party who can supply binary content to such an application can thereby cause additional elements to be inserted into, or existing elements to be removed from, the database command the application issues, without needing any database credentials of their own. This can result in unauthorized modification of stored data and disclosure of data outside the intended scope of the application's request, bounded by the database privileges the application itself holds.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- MongoDB / C# Driver: ≥ 2.0.0; < 3.13.0 (affected, semver). Source: CNA: mongodb

## Severity and prioritization

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: mongodb

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N; source: CNA: mongodb

- CISA KEV: No listing in collected sources

- EPSS: 0.26% as of 2026-11-02; percentile 18.13%

- SSVC: exploitation poc; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-130

## Exploit evidence

- exploit: https://github.com/mongodb/mongo-csharp-driver/security/advisories/GHSA-5chr-phc4-wcj2 (ADP: CISA-ADP)

## References

- https://jira.mongodb.org/browse/CSHARP-6157 (CNA: mongodb)

- https://github.com/mongodb/mongo-csharp-driver/releases/tag/v3.13.0 (CNA: mongodb)

- https://github.com/mongodb/mongo-csharp-driver/security/advisories/GHSA-5chr-phc4-wcj2 (CNA: mongodb)

- https://github.com/mongodb/mongo-csharp-driver/security/advisories/GHSA-5chr-phc4-wcj2 (ADP: CISA-ADP; exploit)

## Provenance

- CNA: mongodb: https://www.cve.org/CVERecord?id=CVE-2026-114646; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-114646; retrieved 2026-11-02; source updated Not reported

Revision: 172b616dc4ddf51900e3302753299bab70e655d88f17c37c65b60e4e768f1807

Canonical: https://y2.dev/cve/CVE-2026-114646

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