CVE-2019-5883 in Community Edition
Summary
by MITRE
An Incorrect Access Control issue was discovered in GitLab Community and Enterprise Edition 6.0 and later but before 11.3.11, 11.4.x before 11.4.8, and 11.5.x before 11.5.1. The issue comments feature could allow a user to comment on an issue which they shouldn't be allowed to.
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Analysis
by VulDB Data Team • 09/22/2023
The vulnerability identified as CVE-2019-5883 represents a critical access control flaw in GitLab's issue tracking system that persisted across multiple versions of both Community and Enterprise editions. This security weakness specifically targeted the comments functionality within GitLab's issue management system, creating a scenario where unauthorized users could gain access to comment on issues they should not have permission to interact with. The vulnerability affected a broad range of GitLab installations, spanning from version 6.0 through the affected release branches up to version 11.5.0, making it a widespread concern for organizations relying on GitLab for their source code management and collaboration workflows.
The technical implementation of this access control flaw stemmed from inadequate validation of user permissions within the issue commenting mechanism. When users attempted to submit comments to specific issues, the system failed to properly verify whether the requesting user possessed the appropriate authorization level to engage with that particular issue. This failure allowed users with lower privilege levels to bypass normal access controls and post comments to issues that were restricted to specific user groups or project members. The flaw essentially created a backdoor pathway through which unauthorized parties could inject content into project discussions, potentially leading to information disclosure or malicious commentary within protected project contexts.
The operational impact of this vulnerability extended beyond simple unauthorized commenting, as it represented a fundamental breakdown in GitLab's permission model that could compromise project integrity and confidentiality. Organizations utilizing GitLab for sensitive development work or private repositories faced significant risks when this vulnerability was present, as attackers could exploit it to gain insights into project discussions, potentially uncovering implementation details, security concerns, or other sensitive information shared within restricted issue threads. The vulnerability could also enable social engineering attacks where malicious users might post misleading information or propaganda within project contexts, undermining trust in the development process and potentially causing confusion among legitimate project participants.
Mitigation strategies for CVE-2019-5883 required immediate patch application to affected GitLab installations, with administrators prioritizing upgrades to versions 11.3.11, 11.4.8, or 11.5.1, which contained the necessary fixes for the access control mechanism. Organizations should also implement comprehensive monitoring of issue commenting activities to detect any unauthorized access patterns that might have occurred during the vulnerability window. The fix addressed the core issue by strengthening the permission validation process within the comments feature, ensuring that all comment submissions undergo proper authorization checks before being processed. Security teams should consider implementing additional controls such as comment moderation workflows and access logging to provide enhanced oversight of collaborative activities within their GitLab environments. This vulnerability aligns with CWE-285, which addresses improper authorization in software systems, and represents a clear violation of the principle of least privilege that should govern all access control mechanisms in development platforms.
The incident highlighted the critical importance of maintaining up-to-date security practices within development toolchains, as even seemingly minor access control flaws can create significant security risks in collaborative environments. Organizations should establish robust patch management procedures and regularly audit their development platform configurations to prevent similar vulnerabilities from persisting in their infrastructure. The vulnerability also demonstrated the need for continuous security testing of core application features, particularly those involving user interactions and permission handling that form the foundation of collaborative development platforms.