Description

GitLab has remediated an issue in GitLab EE affecting all versions from 11.3 before 19.1.7, 19.2 before 19.2.5, and 19.3 before 19.3.1 that, under certain conditions, an authenticated user with project Maintainer permissions could have accessed the terminal of a protected environment they were not authorized to use due to improper authorization checks.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.5",
  "pubDate": "2026-08-26T14:17:10.680Z",
  "pubdate": "2026-08-26T14:17:10.680Z",
  "executiveSummary": "This vulnerability is an authorization bypass flaw identified within GitLab EE that permits authenticated users possessing project Maintainer permissions to gain unauthorized access to protected environment terminals.\nThe vulnerability stems from improper authorization checks during the terminal initiation process for protected environments, which are designed to be restricted based on specific user permissions or environment-level security constraints.\nThe scope of impact includes all GitLab EE versions from 11.3 prior to 19.1.7, 19.2 before 19.2.5, and 19.3 before 19.3.1.\nThe primary risk implication is a compromise of environment isolation, potentially leading to unauthorized command execution, data exfiltration, or lateral movement within the deployment infrastructure linked to the GitLab environment.\nSuccessful exploitation requires the attacker to hold Maintainer-level access to the project, effectively escalating their privilege to interact with environments that should be restricted.\nNo external network exposure is required for the initial access, as the vulnerability resides within the internal logic of the GitLab application's authorization framework.",
  "technicalDetails": "The root cause of this vulnerability lies in an insufficient validation of user privileges when accessing terminals associated with protected environments in GitLab EE. While GitLab employs a robust Role-Based Access Control (RBAC) model to govern deployment and environment access, the implementation of authorization checks for terminal sessions failed to adequately verify whether a user—even those with high-level project permissions like Maintainer—is explicitly authorized to access a specific protected environment.\nUnder normal operating conditions, protected environments should strictly limit terminal access to authorized users or roles defined in the environment's configuration. However, due to the flaw, the application's backend logic for validating environment access bypasses these checks, assuming that project-level Maintainer permissions are sufficient to bypass environment-specific restrictions.\nThe attack flow begins with an authenticated attacker possessing Maintainer permissions navigating to the CI/CD environment settings for a project. Even if the environment is configured as 'protected' and the user is not listed within the authorized access list, the application fails to perform a secondary, rigorous check against the environment-level policy engine. Instead, the system validates the session based solely on the user's project role.\nUpon reaching the terminal interface of the protected environment, the application initiates a connection request. Because the authorization logic is flawed, the request is processed and accepted by the server. The server subsequently establishes a terminal session within the target environment, granting the attacker the ability to execute commands in the context of the environment’s service runner.\nThe post-exploitation impact allows the attacker to execute arbitrary commands on the runner associated with the protected environment. This is a critical security violation because protected environments often contain sensitive credentials, environment variables, or infrastructure access tokens intended for production deployments. By leveraging the terminal, an attacker can extract these secrets, modify build artifacts, or pivot into the production infrastructure to conduct further malicious activities.\nThis vulnerability highlights a critical failure in the synchronization between project-level RBAC and granular resource-level authorization within GitLab EE's internal security architecture. The affected versions (11.3 through 19.3.1) exhibit this logic error, necessitating a patch to enforce explicit environment-level authorization checks before terminal instantiation."
}