CVE WatchNov 10, 2026

CVE-2026-120809

A use-after-free read issue exists in MongoDB’s SBE (Slot-Based Execution) engine when processing aggregation pipelines with $unwind on time

CVSS

6.8

Medium

EPSS

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KEV

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Exploit Today

0-100

Published: Nov 10, 2026 · Last modified: Nov 10, 2026 · CWE-416

EPSS · 30d

Not enough EPSS history yet.

Technical 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.

Official references

jira.mongodb.orghttps://jira.mongodb.org/browse/SERVER-132279

Related CVEs

CVECVSSEPSSKEVRExploitTitleMod.

CVE-2026-1208115.9 MED

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——0A use-after-free issue exists in the MongoDB server’s classic query engine plan cache. Under certain query conditions, an unowned reference to data from an earlier command can be retained in cached plan statistics. After the originating memory is freed, a subsequent diagnostic command serializing those statistics can read freed heap memory, potentially returning sensitive server process memory contents to the authenticated client. Under certain heap reuse conditions, this may also cause the server to crash.3h CVE-2026-1208037.1 HIG

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——0A use-after-free issue exists in MongoDB’s SBE (Slot-Based Execution) implementation of a window function accumulator used by certain $setWindowFields aggregation pipelines. Under specific conditions, the accumulator can retain a dangling pointer to memory that has since been freed. When this stale pointer is later dereferenced during serialization of the carried-forward value, it can result in a heap out-of-bounds read that may expose adjacent heap contents and crash the mongod server. An authenticated user with readWrite privileges on a database can trigger this issue by crafting a specific aggregation pipeline.3h CVE-2026-969947.0 HIG

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