ExpressionContext use-after-free in classic engine $lookup and $graphLookup aggregation operators
CVE-2026-4148 is fixed in MongoDB on 1 platform by MongoDB 8.2.6 (version 8.2.6), released February 25, 2026. It is not reported as exploited. Patch Radar priority: High.
A use-after-free vulnerability can be triggered in sharded clusters by an authenticated user with the read role who issues a specially crafted $lookup or $graphLookup aggregation pipeline.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Windows apps | |||
| MongoDB | 8.2.6 | MongoDB 8.2.6 | Feb 25, 2026 |
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