Description

In JetBrains YouTrack before 2026.2.18634 unchecked group membership changes allowed privilege escalation

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-09-07T17:17:26.383Z",
  "pubdate": "2026-09-07T17:17:26.383Z",
  "executiveSummary": "A critical security vulnerability identified in JetBrains YouTrack allows unauthorized privilege escalation through improper handling of group membership modifications.\nThe vulnerability is categorized as a failure in access control, specifically regarding the verification of group membership change requests.\nBy manipulating group membership parameters, an authenticated attacker can grant themselves elevated roles or administrative privileges within the YouTrack environment.\nThe vulnerability affects all JetBrains YouTrack versions prior to 2026.2.18634.\nThe primary risk implication is a total compromise of the application's authorization model, allowing malicious actors to perform administrative actions, access sensitive project data, or modify system configurations.\nSuccessful exploitation requires the attacker to have an existing authenticated session, but it does not inherently require administrative access prior to the escalation attempt.\nGiven the nature of YouTrack as a centralized issue tracking and project management system, this flaw poses a severe risk to organizational data integrity and confidentiality.",
  "technicalDetails": "The root cause of this vulnerability lies in an inadequate validation mechanism within the YouTrack group management subsystem. Specifically, the application failed to properly perform authorization checks when processing requests to modify group memberships, assuming that the requester was authorized to perform such operations or failing to re-verify the integrity of the membership change request.\nThe vulnerability exists within the backend components responsible for processing administrative group synchronization and user management API endpoints. The lack of strict access control checks on these endpoints allows an attacker to inject requests that alter the security posture of their own account or another user's account.\nThe attack flow proceeds as follows: First, the attacker identifies the API endpoints responsible for group assignment and modification. Second, the attacker crafts a malicious request aimed at altering the group membership of their target account. Due to the lack of server-side validation, the backend processes the request as if it originated from a highly privileged user, successfully updating the user's role mappings within the database.\nOnce the group membership is updated, the attacker gains the permissions associated with the newly assigned group. In scenarios where a user is added to an administrative group, the attacker effectively gains full control over the YouTrack instance. This allows for persistent access and potential lateral movement if the YouTrack instance is integrated with external identity providers or enterprise directory services.\nThis vulnerability is particularly dangerous because it bypasses the expected Principle of Least Privilege. The system assumes that standard users lack the capability to interact with the group management logic; however, the lack of input/request validation on these specific endpoints enables an escalation path that does not trigger standard security alerts.\nPost-exploitation impact includes unauthorized access to private issue trackers, modification of global system settings, and potential for data exfiltration. The exploitation is silent, as it leverages legitimate system APIs to perform state changes, often bypassing basic signature-based detection mechanisms that might otherwise monitor for unauthorized login attempts or abnormal traffic patterns."
}