CVE-2026-82059

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MongoDB Server Assertion Failure via Malformed Index Specification

Publication date: 2026-09-08

Last updated on: 2026-09-08

Assigner: MongoDB, Inc.

Description

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.

CVSS Scores

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Meta Information

Published

2026-09-08

Last Modified

2026-09-08

Generated

2026-09-29

AI Q&A

2026-09-10

EPSS Evaluated

2026-09-27

NVD

CVE-2026-82059

Affected Vendors & Products

Vendor	Product	Version / Range
mongodb	mongodb_server	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-617	The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Attack-Flow Graph

Executive Summary

This vulnerability in MongoDB Server involves an internal aggregation expression that was incorrectly made accessible to any authenticated user instead of being restricted to internal cluster operations. An attacker with read-only privileges could exploit this by crafting a malformed index specification, triggering an assertion failure in the index key generation code path. In some build configurations, this causes the mongod process to terminate, leading to a denial of service for all connected clients.

Detection Guidance

This vulnerability may be detected by monitoring for unexpected mongod process terminations or crashes, particularly after index operations. Check MongoDB logs for assertion failures related to index key generation. No specific commands are provided in the context.

Impact Analysis

If you use MongoDB Server, an attacker with read-only access could exploit this flaw to crash the database server. This would disrupt all database operations, making the system unavailable to legitimate users and applications until the server is restarted.

Compliance Impact

This vulnerability could lead to service disruption, which may violate availability requirements in GDPR and HIPAA. Downtime could result in unauthorized data access or loss, potentially breaching compliance with these regulations.

Mitigation Strategies

Upgrade MongoDB to a patched version where this issue is resolved. Restrict authenticated user privileges to the minimum required. Monitor for unusual index operations or crashes.

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