CVE-2026-4148 ExpressionContext use-after-free in classic engine $lookup and $graphLookup aggregation operators
An authenticated user can trigger a use-after-free in sharded clusters via crafted aggregation pipelines, potentially leading to code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-4148?
CVE-2026-4148 is a high-severity use after free vulnerability in Mongodb Mongodb, published on 17 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-416
Which versions are affected by CVE-2026-4148?
1 open source package ship an affected version, including mongodb. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
mongodb Bitnami | From 7.0.0 | 7.0.31, 8.0.20, 8.2.6, 8.3.1 |
Products include Mongodb Mongodb.
How do I fix CVE-2026-4148?
Upgrade mongodb to a fixed version for your release line: 7.0.31, 8.0.20, 8.2.6 or 8.3.1.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-4148 being exploited?
There is no known exploitation of CVE-2026-4148 in the wild and no public exploit code.
Other vulnerabilities in Mongodb Mongodb
- CVE-2025-14847 MongoDB and MongoDB Server Improper Handling of Length Parameter Inconsistency
- CVE-2026-82067 Auth bypass in MongoDB Server
- CVE-2026-13072 MongoDB Improper Input Validation in Compute Mode External Data Processing Leading to Memory Corruption
- CVE-2017-15535 Denial of service in n/a
- CVE-2026-18691 Improper Authentication in MongoDB Intra-Cluster Connections Allows Credential Exposure
Sources
Also known as BIT-mongodb-2026-4148, GHSA-5rch-679r-cv33, MINI-3jrf-4c4g-6hm2, MINI-7r87-j66j-58x2, UBUNTU-CVE-2026-4148.