Description

An issue in MongoDB Server could allow a party with a valid client certificate and a corresponding user account to authenticate using a certificate-based authentication method, even when an administrator has configured the server to restrict authentication to other mechanisms. This could allow authentication through a method the administrator intended to disable.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "4.2",
  "pubDate": "2026-08-11T19:17:24.900Z",
  "pubdate": "2026-08-11T19:17:24.900Z",
  "executiveSummary": "An improper authentication restriction vulnerability has been identified within MongoDB Server that impacts system security posture and administrative controls.\nThe vulnerability allows an authenticated entity possessing a valid client certificate and a corresponding user account to successfully authenticate via certificate-based authentication mechanisms.\nThis behavior occurs regardless of explicit administrative configurations intended to disable or restrict authentication to alternative mechanisms.\nThe primary impact of this flaw is the circumvention of administrative security policies, enabling unauthorized utilization of disabled authentication pathways.\nAttackers must possess a valid client certificate and a corresponding user account on the target MongoDB Server to successfully exploit this security deficiency.\nThe risk implications involve the potential failure of access control segmentation and policy enforcement, increasing the attack surface by permitting unintended authentication vectors.\nNo specific version numbers, CWE identifiers, or CVE identifiers are provided in the input context, restricting the scope of affected product versions exclusively to the generalized MongoDB Server description.",
  "technicalDetails": "The root cause of the vulnerability lies in the logic governing authentication mechanism enforcement within MongoDB Server, where administrative restrictions intended to disable certificate-based authentication fail to properly reject incoming certificate-based connection attempts.\nThe vulnerable component involves the server-side authentication subsystem responsible for validating and enforcing allowed authentication protocols and mechanisms against configured administrative policies.\nExploitation requires the attacker to possess a valid client cryptographic certificate and an active corresponding user account provisioned within the MongoDB Server environment.\nThe attack flow initiates when an administrator explicitly configures the MongoDB Server to restrict or disable certificate-based authentication in favor of other mechanisms.\nDespite this configuration, a malicious or unauthorized party initiates a TLS handshake presenting a valid client certificate mapped to a corresponding user account.\nThe MongoDB Server authentication handler improperly evaluates the connection request, bypassing the administrative restriction checks and successfully validating the client certificate.\nConsequently, the server grants access via the certificate-based authentication method that the administrator specifically intended to disable.\nThe network exposure relies on the accessibility of the MongoDB Server network port where client connections and TLS handshakes are accepted.\nPrivilege requirements include having a pre-existing user account and a valid client certificate recognized by the server's trust store.\nPost-exploitation impact includes unauthorized session establishment via a prohibited authentication vector, potentially granting access inconsistent with the intended security policy and facilitating further unauthorized database operations depending on the user account permissions."
}