CVE-2026-10518 in GitLab
Summary
by MITRE • 09/29/2026
GitLab has remediated an issue in GitLab EE affecting all versions from 17.9 before 19.2.7, 19.3 before 19.3.3, and 19.4 before 19.4.1 that under certain conditions could have allowed an authenticated user with guest-level permissions to read private security policy content they were not authorized to access due to improper authorization enforcement.
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Analysis
by VulDB Data Team • 09/29/2026
GitLab has addressed a critical authorization bypass vulnerability affecting its Enterprise Edition across multiple recent release branches, specifically versions 17.9 prior to 19.2.7, 19.3 prior to 19.3.3, and 19.4 prior to 19.4.1. This flaw stems from an improper implementation of access control mechanisms within the security policy management subsystem. The vulnerability allows authenticated users who possess only guest-level permissions on a project or group to bypass intended restrictions and read sensitive private security policy content. In typical GitLab deployments, guest accounts are granted minimal privileges designed primarily for viewing code and participating in basic discussions, while higher-tier roles such as developers, maintainers, or owners hold exclusive rights to manage security configurations, including secret detection rules, dependency scanning policies, and other compliance-related settings. The failure to enforce these boundaries represents a significant deviation from the principle of least privilege, which is foundational to secure software architecture.
The technical nature of this flaw aligns with CWE-284, Improper Access Control, where the application fails to correctly verify that an authenticated user has sufficient privileges for the requested action. Furthermore, it relates closely to CWE-639, Authorization Bypass Through User-Controlled Key, if the vulnerability exploits specific identifiers or parameters within API calls or web requests to circumvent server-side checks. From a threat modeling perspective using the MITRE ATT&CK framework, this behavior is indicative of T1078, Valid Accounts, as it leverages legitimate but low-privileged credentials to access restricted resources. It also touches upon aspects of privilege escalation in terms of information disclosure, allowing an attacker with minimal initial access to gather intelligence about security configurations that could inform further attacks against the organization's infrastructure.
The operational impact of this vulnerability is substantial for organizations relying on GitLab as their primary DevSecOps platform. Security policies often contain sensitive details regarding internal threat models, specific secret detection patterns tailored to proprietary codebases, and compliance requirements mandated by regulatory bodies such as GDPR or HIPAA. Unauthorized access to these documents could reveal architectural weaknesses, expose internal security tooling configurations, or provide adversaries with insights into how the organization detects and responds to threats. This information leakage can facilitate more sophisticated attacks, including targeted phishing campaigns based on known security controls or attempts to bypass detection mechanisms by understanding their logic. For enterprises undergoing audits, this flaw also poses a compliance risk as it undermines the integrity of access control logs and policies intended to protect sensitive intellectual property and regulatory data.
Mitigation requires immediate action from system administrators and DevOps teams responsible for maintaining GitLab instances. The primary remediation step is to upgrade all affected Enterprise Edition installations to their respective patched versions: 19.2.7 or later, 19.3.3 or later, or 19.4.1 or later. During the transition period, organizations should review audit logs for any anomalous access patterns by guest users attempting to interact with security policy endpoints. Additionally, it is advisable to conduct a comprehensive review of user permissions across all projects and groups to ensure that no unintended elevations have occurred due to misconfigurations exacerbated by this flaw. Future development practices should incorporate rigorous unit testing for authorization logic in new features involving sensitive data access, ensuring that every endpoint validates the caller's role against explicit allowlists rather than relying on implicit assumptions about user hierarchy. Regular penetration testing focused on horizontal and vertical privilege escalation vectors will further strengthen the security posture of GitLab deployments.