CVE-2026-25610: MongoDB $geoNear DoS Vulnerability

CVE-2026-25610 Overview

CVE-2026-25610 is a denial of service vulnerability in MongoDB Server that allows an authorized user to trigger a server crash by running a $geoNear aggregation pipeline with certain invalid index hints. This vulnerability stems from improper assertion handling (CWE-617) when processing malformed geospatial query parameters.

Critical Impact

Authorized users can crash the MongoDB server, causing service disruption and potential data availability issues for all connected applications and services.

Affected Products

• MongoDB Server (specific versions not disclosed in advisory)

Discovery Timeline

• 2026-02-10 - CVE-2026-25610 published to NVD
• 2026-02-10 - Last updated in NVD database

Technical Details for CVE-2026-25610

Vulnerability Analysis

This vulnerability is classified as CWE-617 (Reachable Assertion), which occurs when the MongoDB server encounters an assertion failure during the processing of geospatial queries. The $geoNear aggregation stage is designed to return documents sorted by proximity to a specified point, requiring appropriate geospatial indexes. When an authorized user provides invalid index hints to this pipeline stage, the server fails to properly validate or handle the malformed input, triggering an internal assertion that crashes the server process.

The network-accessible nature of this vulnerability means any authenticated user with query privileges can potentially exploit it remotely without any user interaction required.

Root Cause

The root cause of this vulnerability lies in inadequate input validation within the $geoNear pipeline stage's index hint processing logic. When the server receives an invalid index hint for a geospatial query, it encounters an unexpected state that triggers a reachable assertion. Rather than gracefully handling the error condition and returning an appropriate error message to the client, the assertion causes the entire server process to terminate.

This represents a classic case of defensive programming failure where assertions intended for development-time debugging remain active in production code paths, creating a denial of service attack surface.

Attack Vector

The attack can be executed by any authenticated user with permissions to run aggregation pipelines against the database. The attacker constructs a $geoNear aggregation query with specially crafted invalid index hints. When the MongoDB server processes this query, it encounters the assertion failure and crashes.

The attack requires only network access to the MongoDB instance and valid authentication credentials with basic query permissions. No special privileges or complex chaining of vulnerabilities is necessary to exploit this issue.

For technical details on the specific invalid index hint patterns that trigger this vulnerability, refer to the MongoDB Server Issue Tracker.

Detection Methods for CVE-2026-25610

Indicators of Compromise

• Unexpected MongoDB server process terminations or restarts
• Assertion failure messages in MongoDB server logs related to $geoNear or index hint processing
• Unusual aggregation pipeline queries with $geoNear stages containing malformed or unexpected index hints
• Repeated authentication attempts followed by server crashes from the same client

Detection Strategies

• Monitor MongoDB server logs for assertion failures (SIGABRT signals or assertion messages)
• Implement query auditing to track all $geoNear aggregation pipeline executions
• Set up alerting for unexpected server process restarts or terminations
• Review authentication logs for patterns of access preceding crash events

Monitoring Recommendations

• Configure MongoDB monitoring tools to alert on server availability gaps
• Enable the database profiler to capture slow or suspicious aggregation queries
• Implement health checks that detect rapid server restart cycles
• Use SentinelOne Singularity platform to monitor for anomalous process behavior and unexpected service terminations

How to Mitigate CVE-2026-25610

Immediate Actions Required

• Review and restrict database user permissions to limit who can execute aggregation pipelines
• Implement application-level validation of index hints before passing to MongoDB
• Enable MongoDB authentication and authorization if not already configured
• Monitor for exploitation attempts using the detection strategies outlined above

Patch Information

Refer to the MongoDB Server Issue Tracker for official patch information and updated versions. Apply the vendor-provided security patches as soon as they become available. Ensure your MongoDB deployment is updated to a patched version that addresses this assertion failure vulnerability.

Workarounds

• Restrict network access to MongoDB servers using firewall rules and network segmentation
• Limit the use of $geoNear aggregation pipelines to trusted applications only
• Implement a proxy or middleware layer that validates aggregation queries before forwarding to MongoDB
• Configure automatic server restart and monitoring to minimize downtime impact if exploitation occurs

# Example: Restrict MongoDB network access via firewall
# Allow connections only from trusted application servers
iptables -A INPUT -p tcp --dport 27017 -s 10.0.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 27017 -j DROP

# Enable MongoDB authorization in mongod.conf
# security:
#   authorization: enabled