CVE-2026-25613: MongoDB Server DOS Vulnerability

CVE-2026-25613 Overview

CVE-2026-25613 is a Denial of Service vulnerability in MongoDB that allows an authorized user to disable the MongoDB server by issuing a query against a collection containing an invalid compound wildcard index. This vulnerability is classified as a Type Confusion issue (CWE-704), where the server improperly handles type casting or incorrect type assumptions when processing certain query operations.

Critical Impact

An authenticated attacker with query privileges can crash the MongoDB server, causing service disruption for all connected applications and users relying on the database.

Affected Products

• MongoDB Server (affected versions not specified in advisory)

Discovery Timeline

• 2026-02-10 - CVE-2026-25613 published to NVD
• 2026-02-10 - Last updated in NVD database

Technical Details for CVE-2026-25613

Vulnerability Analysis

This vulnerability stems from improper handling of invalid compound wildcard indexes within MongoDB's query processing engine. When an authorized user executes a query against a collection that contains a malformed or invalid compound wildcard index, the server fails to properly validate or handle the index structure, leading to a crash condition.

The attack requires network access and authenticated credentials with at least basic query privileges on the target collection. While user interaction is not required, the attacker must have legitimate access to issue queries, which limits the attack surface to authenticated users within the database environment.

The impact is confined to availability—there is no unauthorized data access or modification. However, a successful exploitation results in complete service disruption, affecting all database operations and connected applications.

Root Cause

The root cause is a Type Confusion vulnerability (CWE-704) in MongoDB's index processing logic. When the query engine encounters a compound wildcard index that contains invalid or unexpected type configurations, the server fails to properly cast or validate the index metadata. This results in the server attempting to process data structures in an incompatible manner, triggering an unhandled exception that crashes the database service.

Compound wildcard indexes are a complex feature that combines multiple field paths with wildcard operators. The vulnerability likely exists in the code path that validates and interprets these index definitions during query planning or execution phases.

Attack Vector

The attack vector is network-based, requiring the attacker to have authenticated access to the MongoDB instance. The attack flow involves:

1. The attacker identifies or creates a collection with an invalid compound wildcard index
2. The attacker issues a query that causes the query engine to access or evaluate the malformed index
3. The server encounters the type confusion condition during index processing
4. The unhandled exception causes the MongoDB server process to terminate

This vulnerability does not require any user interaction beyond the attacker's own actions, and the attack complexity is low once the prerequisite access is obtained. Additional details regarding the specific query patterns and index configurations that trigger this condition can be found in the MongoDB Jira Issue SERVER-113685.

Detection Methods for CVE-2026-25613

Indicators of Compromise

• Unexpected MongoDB server crashes or restarts without clear system resource issues
• Database logs showing unhandled exceptions related to index processing or query planning
• Evidence of queries targeting collections with complex or unusual compound wildcard indexes
• Repeated authentication from specific users followed by server availability issues

Detection Strategies

• Monitor MongoDB server logs for crash events, particularly those mentioning index-related errors or type confusion conditions
• Implement alerting on unexpected mongod process terminations or restart patterns
• Audit query patterns from authenticated users, especially those targeting collections with wildcard indexes
• Review index definitions across collections to identify potentially malformed compound wildcard indexes

Monitoring Recommendations

• Enable verbose logging for index operations and query planning phases
• Configure process monitoring to alert on MongoDB daemon crashes with automatic restart detection
• Implement database availability monitoring with rapid alerting for service interruptions
• Track authentication events correlated with server stability metrics to identify potential malicious actors

How to Mitigate CVE-2026-25613

Immediate Actions Required

• Review all compound wildcard indexes in production databases for validity and proper configuration
• Audit user permissions to ensure query access is limited to necessary accounts only
• Implement monitoring for server crashes and unusual query patterns
• Consider temporarily restricting access to collections with complex wildcard indexes until patches are applied

Patch Information

MongoDB has acknowledged this issue in Jira Issue SERVER-113685. Administrators should monitor the official MongoDB security advisories and release notes for patch availability. Apply the security update as soon as it becomes available through official MongoDB distribution channels.

Workarounds

• Audit and validate all compound wildcard indexes in the database, removing or recreating any that appear malformed
• Restrict database user privileges to the minimum necessary, limiting who can execute arbitrary queries
• Implement network-level access controls to limit which systems can connect to the MongoDB instance
• Consider using MongoDB's authentication and authorization features to enforce stricter access policies on sensitive collections

Administrators can audit existing indexes using the MongoDB shell:

# List all indexes in the current database to audit for compound wildcard indexes
mongo --eval "db.getCollectionNames().forEach(function(c) { print('Collection: ' + c); printjson(db[c].getIndexes()); })"