Is CVE-2026-120818 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-120818 being exploited in the wild.

How severe is CVE-2026-120818?

High severity, with a CVSS score of 7.1, published 10 November 2026.

Which products and versions are affected?

MongoDB Server 7.0.0 through 8.3.0 before fixes.

Is there a fix for CVE-2026-120818?

Yes: fixed in MongoDB Server 7.0.48, 8.0.37, 8.3.16. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-120818 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-120818?

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.

CVE-2026-120818: MongoDB Server use-after-free in server-side JavaScript aggregation

CVE-2026-120818 · Severity: high · CVSS 7.1 · Published 2026-11-10

MongoDB Server's server-side JavaScript engine for aggregation queries contains a use-after-free vulnerability that allows authenticated users to read freed memory. An attacker can submit a crafted aggregation request to retrieve sensitive data from the server process, including memory layout information that bypasses security protections, and potentially cause the server to become unavailable.

Technologies: MongoDB Server. Vendors: MongoDB.

Quick answers

Is CVE-2026-120818 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-120818 being exploited in the wild.
How severe is CVE-2026-120818?: High severity, with a CVSS score of 7.1, published 10 November 2026.
Which products and versions are affected?: MongoDB Server 7.0.0 through 8.3.0 before fixes.
Is there a fix for CVE-2026-120818?: Yes: fixed in MongoDB Server 7.0.48, 8.0.37, 8.3.16. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-120818 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-120818?: 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

Technical details

A use-after-free vulnerability exists in the legacy MozJS JavaScript engine when processing $accumulator aggregation functions, where advanceGeneration() is not called before entering the function scope, allowing stale references to previously freed global objects to be read. An authenticated user with minimal privileges can trigger this over the network by submitting a specially crafted aggregation pipeline, resulting in unauthorized disclosure of adjacent process memory contents and potential information leaks that undermine memory layout randomization (ASLR).

Affected products

MongoDB MongoDB Server 7.0.0 through 8.3.0 before fixes

Timeline

2026-11-10: disclosed
2026-10-01: patched

References

https://jira.mongodb.org/browse/SERVER-135727

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