CVE-2026-82059: Improper Access Restriction of Internal Aggregation Expression in MongoDB Server Leads to Assertion Failure and Denial of Service
An internal aggregation expression in MongoDB Server was incorrectly registered as accessible to any authenticated user rather than being restricted to internal cluster operations. By crafting a malformed index specification within this expression, an authenticated user with read-only privileges could trigger an assertion failure in the index key generation code path. In certain build configurations, this assertion failure results in termination of the mongod process, causing a denial of service to all connected clients.
Affected Software
Event History
Frequently Asked Questions
Who can exploit this issue?
An authenticated MongoDB user with read-only privileges can reach the incorrectly exposed internal aggregation expression. Exploitation requires crafting a malformed index specification and has high attack complexity.
Are deployments affected by default?
The issue is exposed to authenticated users because the expression was registered as accessible to any authenticated user instead of only internal cluster operations. Whether successful exploitation terminates mongod depends on the build configuration.
What is the impact of successful exploitation?
A successful attempt can trigger an assertion failure in the index key generation path. In certain build configurations, this terminates the mongod process and denies service to all connected clients.
What can be done if patching is not immediately possible?
Restrict access for read-only and other nonessential authenticated users, since authenticated users can access the affected expression. Limit database access to trusted accounts and internal cluster operations where possible.