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

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. 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

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