# CVE-2026-120813: MongoDB Server client-side field-level encryption schema parsing bypass

Source: https://junglewise.ai/threats/cve-2026-120813-an-issue-in-mongodb-server-s-client-side-field-level-encryption  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-120813 · Severity: medium · CVSS 5.9 · Published 2026-11-10

MongoDB Server's client-side field-level encryption (CSFLE) can silently drop encryption metadata when processing malformed schemas, causing sensitive data to be stored unencrypted. An attacker positioned to intercept or control the schema delivered to a user's CSFLE client—such as through a compromised server or man-in-the-middle attack—can trick the client into storing plaintext data that should be encrypted, defeating the encryption protections entirely.

Technologies: [MongoDB Server](https://junglewise.ai/threats/technologies/mongodb-server). Vendors: [MongoDB](https://junglewise.ai/threats/vendors/mongodb).

## Quick answers

**Is CVE-2026-120813 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-120813 being exploited in the wild.

**How severe is CVE-2026-120813?** Medium severity, with a CVSS score of 5.9, published 10 November 2026.

**Which products and versions are affected?** MongoDB Server 7.0.x before 7.0.48, 8.0.x before 8.0.37, 8.3.x before 8.3.16, 9.0.x before 9.0.7.

**Is there a fix for CVE-2026-120813?** Yes: fixed in Server 7.0.48, 8.0.37, 8.3.16, 9.0.7. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-120813 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-120813?** Check whether you run MongoDB Server at an affected version. 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.

## How to fix

- Fixed in Server 7.0.48, 8.0.37, 8.3.16, 9.0.7

## Technical details

The CSFLE schema processing component uses a "last-wins" map assignment for duplicate `properties` keys and "first-wins" set insertion for duplicate `patternProperties` patterns, silently discarding duplicates instead of rejecting them. An attacker can craft a schema with duplicate keys to overwrite or drop encryption directives, causing the client to skip encryption for targeted fields. The vulnerability requires network-level access to deliver the malicious schema to the client.

## Affected products

- MongoDB Server 7.0.x before 7.0.48, 8.0.x before 8.0.37, 8.3.x before 8.3.16, 9.0.x before 9.0.7

## Timeline

- 2026-11-10: disclosed

## References

- [https://jira.mongodb.org/browse/SERVER-132517](https://jira.mongodb.org/browse/SERVER-132517)

## Related threats

- [MongoDB Server authorization bypass in aggregation pipeline](https://junglewise.ai/threats/cve-2026-120825-an-authorization-weakness-in-the-aggregation-framework-of)
- [MongoDB Server use-after-free in time-series bucket validation](https://junglewise.ai/threats/cve-2026-120824-a-use-after-free-in-the-time-series-collection-component-of)
- [MongoDB Server missing authorization check in aggregation framework](https://junglewise.ai/threats/cve-2026-120823-a-missing-authorization-check-in-the-aggregation-framework-of)
- [MongoDB Server authorization bypass in applyOps](https://junglewise.ai/threats/cve-2026-120822-mongodb-server-may-omit-an-authorization-check-on-the-resource)
- [MongoDB Server use-after-free in aggregation framework](https://junglewise.ai/threats/cve-2026-120821-a-use-after-free-in-the-aggregation-framework-of-mongodb-server)