UAF in MongoDB $lookup Aggregation Pipeline
CVE-2026-4148 Published on March 17, 2026
ExpressionContext use-after-free in classic engine $lookup and $graphLookup aggregation operators
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.
Vulnerability Analysis
CVE-2026-4148 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
What is a Dangling pointer Vulnerability?
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
CVE-2026-4148 has been classified to as a Dangling pointer vulnerability or weakness.
Products Associated with CVE-2026-4148
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Affected Versions
MongoDB Inc MongoDB Server:- Version 8.2 and below 8.2.6 is affected.
- Version 8.0 and below 8.0.20 is affected.
- Version 7.0 and below 7.0.31 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.