Description
A use-after-free read issue exists in MongoDB’s SBE (Slot-Based Execution) engine when processing aggregation pipelines with $unwind on time-series collections. An internal error in state-preservation logic can cause a value still referenced by downstream stages to have its underlying memory freed prematurely. An authenticated user can craft an aggregation pipeline under specific conditions to trigger this condition, potentially reading recycled server heap memory in query results or crashing the server. This issue is only triggerable when a non-default server parameter related to the SBE engine is enabled.
Published: 2026-11-10
Score: 6.1 Medium
EPSS: n/a
KEV: No
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History

Tue, 10 Nov 2026 20:15:00 +0000

Type Values Removed Values Added
Description A use-after-free read issue exists in MongoDB’s SBE (Slot-Based Execution) engine when processing aggregation pipelines with $unwind on time-series collections. An internal error in state-preservation logic can cause a value still referenced by downstream stages to have its underlying memory freed prematurely. An authenticated user can craft an aggregation pipeline under specific conditions to trigger this condition, potentially reading recycled server heap memory in query results or crashing the server. This issue is only triggerable when a non-default server parameter related to the SBE engine is enabled.
Title Heap use-after-free read via yield-time state save in time-series block unpacking
Weaknesses CWE-416
References
Metrics cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H'}

cvssV4_0

{'score': 6.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: mongodb

Published:

Updated: 2026-11-10T20:08:12.615Z

Reserved: 2026-11-02T22:54:19.524Z

Link: CVE-2026-120809

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-10T20:18:51.323

Modified: 2026-11-10T20:18:51.323

Link: CVE-2026-120809

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

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Weaknesses