CVE-2019-6995 in Community Edition
Summary
by MITRE
An issue was discovered in GitLab Community and Enterprise Edition 8.x, 9.x, 10.x, and 11.x before 11.5.8, 11.6.x before 11.6.6, and 11.7.x before 11.7.1. It has Incorrect Access Control. Users are able to comment on locked project issues.
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Analysis
by VulDB Data Team • 12/18/2023
The vulnerability identified as CVE-2019-6995 represents a critical access control flaw within GitLab's issue tracking system that persisted across multiple major versions of the platform. This security weakness specifically affects GitLab Community and Enterprise Edition installations running versions 8.x through 11.x, with affected releases including 11.5.7 and earlier, 11.6.5 and earlier, and 11.7.0 and earlier. The flaw allows unauthorized users to bypass intended access restrictions and submit comments to issues that have been explicitly locked by project administrators, thereby undermining the security controls designed to prevent modifications to closed or restricted issues.
The technical nature of this vulnerability stems from inadequate validation of user permissions when processing comment submissions on project issues. In GitLab's intended architecture, locked issues should be protected from further modifications or additions to prevent unauthorized interference with resolved matters. However, the access control implementation fails to properly verify whether the commenting user possesses the appropriate authorization level to interact with locked issues. This flaw operates at the application logic level and constitutes a direct violation of proper access control mechanisms that should enforce mandatory access controls based on user roles and issue states.
The operational impact of this vulnerability extends beyond simple unauthorized commenting, as it compromises the integrity and security of project management workflows within GitLab environments. Administrators who lock issues to prevent further discussion or modifications may unknowingly allow malicious actors or unauthorized users to continue engaging with these restricted items. This capability can be particularly dangerous in enterprise environments where sensitive project data, security vulnerabilities, or confidential business information might be discussed within locked issues. The vulnerability essentially creates a backdoor that allows users to circumvent the intended workflow restrictions, potentially leading to information disclosure, unauthorized modifications, or disruption of project management processes.
Organizations utilizing affected GitLab versions face significant risks including potential data exposure, workflow disruption, and violation of security policies. The vulnerability particularly affects collaborative development environments where project locks are used to manage issue resolution and prevent premature modifications. From a cybersecurity perspective, this issue aligns with CWE-284, which describes improper access control vulnerabilities, and can be categorized under ATT&CK technique T1078 for valid accounts and privilege escalation. The flaw demonstrates a failure in the principle of least privilege, where users can perform actions beyond their authorized scope. Security teams should immediately implement mitigations including upgrading to patched versions, reviewing existing issue locking configurations, and monitoring for unauthorized commenting activities on locked issues. Additionally, organizations should conduct comprehensive security assessments of their GitLab installations to identify other potential access control weaknesses that could similarly compromise project integrity and data protection measures.