# CVE-2026-120815: MongoDB Server authorization bypass via localhost exception

Source: https://junglewise.ai/threats/cve-2026-120815-an-incorrect-authorization-check-in-the-mongodb-server  
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-2026-120815 · Severity: high · CVSS 8.4 · Published 2026-11-10

MongoDB Server with authorization enabled contains a flaw in how it manages the localhost exception, a feature that permits unauthenticated local connections during initial setup. An attacker with local host access can bypass authorization checks if the first user is created in the $external database, allowing them to create administrative accounts and gain full control of the database and its data.

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

## Quick answers

**Is CVE-2026-120815 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-120815 being exploited in the wild.

**How severe is CVE-2026-120815?** High severity, with a CVSS score of 8.4, published 10 November 2026.

**Which products and versions are affected?** MongoDB Server before 7.0.48, before 8.0.37, before 8.3.16, before 9.0.7.

**Is there a fix for CVE-2026-120815?** Yes: fixed in MongoDB 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-2026-120815 attacked?** It is attacked with local access, in a hosted service.

**Am I affected by CVE-2026-120815?** 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 MongoDB Server 7.0.48, 8.0.37, 8.3.16, 9.0.7

## Technical details

An incorrect authorization check in AuthorizationSessionImpl::_getDefaultPrivileges fails to close the localhost exception after a user is created in the $external database, unlike the expected behavior when a user is created in the admin database. An unauthenticated local attacker can exploit this to run privileged createUser commands and obtain root access to the server.

## Affected products

- MongoDB Server before 7.0.48, before 8.0.37, before 8.3.16, before 9.0.7

## Timeline

- 2026-11-10: disclosed: CVE-2026-120815 published

## References

- [https://jira.mongodb.org/browse/SERVER-134872](https://jira.mongodb.org/browse/SERVER-134872)

## 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)