CVE-2018-20802 Post-auth queries on compound index may crash mongod
An authenticated user can crash the MongoDB server by sending specially crafted queries involving compound indexes.
- 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-2018-20802?
CVE-2018-20802 is a medium-severity denial of service vulnerability in Mongodb Mongodb, published on 23 Nov 2020. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A user authorized to perform database queries may trigger denial of service by issuing specially crafted queries with compound indexes affecting QueryPlanner. This issue affects MongoDB Server v3.6 versions prior to 3.6.9 and MongoDB Server v4.0 versions prior to 4.0.3.
Weakness: CWE-394
Which versions are affected by CVE-2018-20802?
It affects 1 product.
Products include Mongodb Mongodb.
How do I fix CVE-2018-20802?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2018-20802 being exploited?
There is no known exploitation of CVE-2018-20802 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 GHSA-g6mr-mvf4-4wvj, UBUNTU-CVE-2018-20802.