CVE-2018-20496 in Community Edition
Summary
by MITRE
An issue was discovered in GitLab Community and Enterprise Edition 11.2.x through 11.4.x before 11.4.13, 11.5.x before 11.5.6, and 11.6.x before 11.6.1. It allows XSS.
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Analysis
by VulDB Data Team • 03/18/2024
This vulnerability represents a cross-site scripting flaw that affected multiple versions of GitLab's web application interface. The issue was present in the community and enterprise editions across specific release ranges including 11.2.x through 11.4.x before 11.4.13, 11.5.x before 11.5.6, and 11.6.x before 11.6.1. The vulnerability stems from inadequate input validation and output encoding mechanisms within the application's user interface components. Attackers could exploit this flaw by injecting malicious script code into user-controllable input fields that were then rendered back to other users without proper sanitization.
The technical implementation of this vulnerability involves the failure to properly escape or encode user-supplied data before displaying it in web pages. When users submitted content containing script tags or other malicious payloads through various interface elements such as issue descriptions, comments, or project names, the application would render this content without sufficient sanitization. This creates a classic XSS attack vector where the malicious scripts execute in the context of other users' browsers, potentially allowing attackers to steal session cookies, perform unauthorized actions, or redirect users to malicious sites. The vulnerability aligns with CWE-79 which specifically addresses Cross-Site Scripting flaws in software applications.
The operational impact of this vulnerability extends beyond simple data theft or defacement. Attackers could leverage this flaw to establish persistent access to GitLab instances by stealing user authentication tokens, enabling them to perform actions as authenticated users. This includes creating new projects, modifying existing repositories, or accessing sensitive code and configuration data. The vulnerability particularly affects collaborative development environments where multiple users interact through shared repositories and issue tracking systems. Organizations using affected GitLab versions faced significant risks to their source code integrity and development workflow security. The attack surface was broad since the vulnerability could be exploited through various user interaction points within the web interface.
Mitigation strategies for this vulnerability primarily involve upgrading to the patched versions of GitLab where the XSS protection mechanisms have been properly implemented. Organizations should immediately apply the security patches released by GitLab for versions 11.4.13, 11.5.6, and 11.6.1 respectively. Additionally, implementing proper input validation at multiple layers including client-side and server-side sanitization provides defense-in-depth. Organizations should also consider deploying web application firewalls and content security policies to further protect against exploitation attempts. The remediation process should include comprehensive testing to ensure that all user input fields properly sanitize and encode content before rendering. Security teams should conduct regular vulnerability assessments and maintain updated threat intelligence to identify similar weaknesses in their GitLab installations. This vulnerability demonstrates the critical importance of proper output encoding and input validation in web applications, aligning with ATT&CK technique T1213 which covers data from information repositories and T1566 which addresses credential access through social engineering and web-based attacks.