Quick answers
- Is CVE-2026-120811 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-120811 being exploited in the wild.
- How severe is CVE-2026-120811?
- Medium severity, with a CVSS score of 5.9, published 10 November 2026.
- Which products and versions are affected?
- MongoDB Server 7.0 before 7.0.48, 8.0 before 8.0.37, 8.3 before 8.3.16, 9.0 before 9.0.7.
- Is there a fix for CVE-2026-120811?
- 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-2026-120811 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-120811?
- 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 classic query engine plan cache where the sort pattern from update and bulkWrite commands is stored as an unowned BSONObj reference into the wire message buffer. After the command completes and the buffer is freed, the $planCacheStats aggregation command can serialize the cached entry, reading the freed heap memory and returning its contents to an authenticated client. This can leak sensitive process memory or trigger a crash via heap corruption under certain reuse conditions.
Affected products
- MongoDB Server 7.0 before 7.0.48, 8.0 before 8.0.37, 8.3 before 8.3.16, 9.0 before 9.0.7
Timeline
- 2026-11-10: disclosed