Description

An issue in MongoDB Server's aggregation framework could allow an unauthenticated party to cause a mongos (router) process to terminate unexpectedly by submitting a specially formed aggregation command. This could result in a denial of service, disrupting client connections routed through the affected mongos instance.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.5",
  "pubDate": "2026-08-11T19:17:23.983Z",
  "pubdate": "2026-08-11T19:17:23.983Z",
  "executiveSummary": "This vulnerability involves a denial of service (DoS) flaw within the MongoDB Server aggregation framework. Specifically, the issue allows an unauthenticated remote attacker to cause the mongos router process to terminate unexpectedly by submitting a specially crafted aggregation command. The affected product is MongoDB Server, specifically impacting the mongos routing component.\nThe risk implication is significant for availability, as the unexpected termination of the mongos process disrupts all active client connections routed through the affected instance, potentially leading to service outages in distributed database deployments. Exploitation of this vulnerability requires network access to the target mongos instance, but does not require authentication or elevated privileges. The attacker's capability is limited to causing a crash (Denial of Service) and does not inherently include remote code execution or data exfiltration based on the provided description.",
  "technicalDetails": "The vulnerability resides within the aggregation framework processing logic of MongoDB Server, specifically handling malformed or specially formed aggregation commands parsed by the mongos router process. The vulnerable component is the mongos routing and query processing engine, which fails to adequately validate or handle specific structural anomalies within incoming aggregation payloads.\nThe attack flow begins when an unauthenticated client establishes a network connection to a target mongos instance and transmits a specially crafted aggregation command. Because the mongos process lacks proper input sanitization or exception handling for this specific command structure, parsing or execution of the payload triggers an unhandled exception or fatal assertion error.\nThis operational failure forces the mongos process to terminate abruptly, dropping all concurrent client sessions and connections routed through that specific instance. While clustering mechanisms or high-availability setups may eventually reroute traffic or allow automatic restarts depending on process supervision configuration, the immediate post-exploitation impact is a localized Denial of Service affecting availability and client connectivity.\nThe requirements for successful exploitation include network reachability to the mongos listening port and the ability to issue database commands. No prior authentication, user credentials, or administrative privileges are required, increasing the exposure if mongos instances are improperly exposed to untrusted networks or the public internet."
}