# CVE-2026-120956: MongoDB C Driver namespace field validation bypass

Source: https://junglewise.ai/threats/cve-2026-120956-the-mongodb-c-driver-does-not-validate-the-type-or-format-of-a  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-03. Updated: 2026-11-03  
License: CC BY 4.0 with a link back

CVE-2026-120956 · Severity: high · CVSS 7.1 · Published 2026-11-03

The MongoDB C Driver fails to validate the namespace field returned by a MongoDB server in query responses, allowing an unauthenticated attacker to send malformed data. This can crash the client application process, leak uninitialized heap memory back to the attacker, and cause out-of-bounds memory reads. The impact is confined to the individual process using the driver, but affects availability and confidentiality for that application.

Technologies: [MongoDB C Driver](https://junglewise.ai/threats/technologies/c-driver). Vendors: [MongoDB](https://junglewise.ai/threats/vendors/mongodb).

## Quick answers

**Is CVE-2026-120956 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-120956 being exploited in the wild.

**How severe is CVE-2026-120956?** High severity, with a CVSS score of 7.1, published 3 November 2026.

**Which products and versions are affected?** MongoDB C Driver.

**Is there a fix for CVE-2026-120956?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-120956 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-120956?** Check whether you run MongoDB C Driver. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The MongoDB C Driver does not validate the type or format of the namespace field returned by a server in query responses. An unauthenticated MongoDB endpoint can return a malformed value in this field, triggering a buffer over-read and causing the client process to crash, while also potentially leaking uninitialized heap memory in a follow-up command to the endpoint.

## Affected products

- MongoDB C Driver

## Timeline

- 2026-11-03: disclosed

## References

- [https://jira.mongodb.org/browse/CDRIVER-6501](https://jira.mongodb.org/browse/CDRIVER-6501)

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