# CVE-2026-120824: MongoDB Server use-after-free in time-series bucket validation

Source: https://junglewise.ai/threats/cve-2026-120824-a-use-after-free-in-the-time-series-collection-component-of  
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-2026-120824 · Severity: high · CVSS 8.8 · Published 2026-11-10

MongoDB Server, a popular database system, has a memory management flaw in its time-series data validation feature that allows an authenticated database user to cause the server to crash or potentially execute arbitrary code. An attacker with write access to a time-series collection can craft a malicious document that triggers the vulnerability during validation, leading to data corruption and server failure.

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

## Quick answers

**Is CVE-2026-120824 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-120824 being exploited in the wild.

**How severe is CVE-2026-120824?** High severity, with a CVSS score of 8.8, published 10 November 2026.

**Which products and versions are affected?** MongoDB Server 8.0.28+, 8.2.12+, 8.3.3+, 9.0.0+.

**Is there a fix for CVE-2026-120824?** 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-2026-120824 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-120824?** 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

A use-after-free vulnerability exists in the time-series bucket validator's FlatBSONStore field lookup mechanism. When merging measurements with conflicting field types (object vs. array), a stale field name map causes duplicate entries with incorrect offsets, leading to out-of-bounds buffer access and heap corruption. The attack requires authenticated database access and a raw insert into a time-series collection; the vulnerability is reachable before the mixed-schema write guard executes.

## Affected products

- MongoDB MongoDB Server 8.0.28+, 8.2.12+, 8.3.3+, 9.0.0+

## Timeline

- 2026-11-10: disclosed
- 2026-11-10: patched

## References

- [https://jira.mongodb.org/browse/SERVER-136505](https://jira.mongodb.org/browse/SERVER-136505)

## 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 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)
- [MongoDB Server memory exhaustion in FLE2 operation statistics](https://junglewise.ai/threats/cve-2026-120820-mongodb-server-maintains-an-in-memory-table-of-per-namespace)