CVE-2019-10111 in Community Edition
Summary
by MITRE
An issue was discovered in GitLab Community and Enterprise Edition before 11.7.8, 11.8.x before 11.8.4, and 11.9.x before 11.9.2. It allows persistent XSS in the merge request "resolve conflicts" page.
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Analysis
by VulDB Data Team • 09/21/2023
The vulnerability CVE-2019-10111 represents a critical persistent cross-site scripting flaw affecting GitLab Community and Enterprise Edition installations across multiple version ranges. This security issue was identified in versions prior to 11.7.8, 11.8.4, and 11.9.2 respectively, exposing organizations to significant risks through the merge request conflict resolution interface. The flaw resides in how the application processes user input within the "resolve conflicts" page, creating an environment where malicious actors can inject persistent script payloads that execute in the context of other users' browsers.
The technical nature of this vulnerability stems from inadequate input validation and output encoding within GitLab's merge request conflict resolution functionality. When users attempt to resolve conflicts in merge requests, the system fails to properly sanitize user-provided content before rendering it in the web interface. This allows attackers to craft malicious input containing script tags or other XSS payloads that persist in the system and execute whenever other users view the affected merge request page. The vulnerability is classified as persistent because the malicious content is stored server-side and affects multiple users over time rather than being a one-time reflected attack vector.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the ability to perform session hijacking, steal sensitive credentials, or redirect users to malicious sites. An attacker who can submit malicious content through the merge request conflict resolution process gains the capability to compromise other users with access to the same GitLab instance. This is particularly concerning in enterprise environments where GitLab serves as a central code collaboration platform, as it can lead to unauthorized access to source code repositories, exposure of sensitive development information, and potential lateral movement within the organization's infrastructure. The vulnerability directly aligns with CWE-79 which categorizes cross-site scripting flaws, and maps to ATT&CK technique T1059.007 for script execution through web applications.
Organizations should immediately implement mitigation strategies including applying the relevant security patches released by GitLab for versions 11.7.8, 11.8.4, and 11.9.2. Additionally, administrators should consider implementing web application firewalls to filter suspicious input patterns and conduct thorough security reviews of user permissions within GitLab installations. Regular security training for developers regarding secure coding practices and input validation techniques should be emphasized to prevent similar vulnerabilities in custom applications. The incident highlights the critical importance of maintaining up-to-date software versions and implementing robust input sanitization measures in collaborative development environments where users can submit content that will be viewed by others.