CVE-2021-22182 in Community Edition
Summary
by MITRE • 03/04/2021
An issue has been discovered in GitLab affecting all versions starting with 13.7. GitLab was vulnerable to a stored XSS in merge request.
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Analysis
by VulDB Data Team • 03/06/2021
The vulnerability identified as CVE-2021-22182 represents a critical stored cross-site scripting flaw within GitLab's merge request functionality that has persisted across all versions beginning with 13.7. This security weakness allows attackers to inject malicious scripts into merge request descriptions, comments, or other user-contributed content that gets stored on the server and subsequently executed in the context of other users' browsers when they view the affected merge requests. The vulnerability stems from insufficient input validation and output encoding mechanisms within GitLab's web application framework, particularly in how it processes and renders user-supplied data within merge request contexts.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious HTML or JavaScript content within a merge request field and submits it to the GitLab instance. When other users navigate to view the merge request containing the malicious payload, their browsers execute the injected scripts in the context of their authenticated sessions. This stored nature of the vulnerability means that the malicious code persists on the server and affects all users who interact with the compromised merge request without requiring repeated exploitation attempts. The flaw primarily resides in GitLab's sanitization processes that should normally filter out potentially dangerous content before rendering it in web interfaces.
The operational impact of CVE-2021-22182 extends beyond simple script execution, as it can enable attackers to perform session hijacking, steal sensitive information, manipulate merge request data, or redirect users to malicious domains. An attacker could potentially escalate privileges by exploiting this vulnerability to access other users' sessions or sensitive project information. The vulnerability affects both the GitLab Community Edition and Enterprise Edition, making it particularly concerning for organizations that rely on GitLab for version control and collaboration. This type of vulnerability aligns with CWE-79 which categorizes cross-site scripting flaws, and represents a significant risk in environments where GitLab serves as a central collaboration platform for software development teams.
Organizations affected by this vulnerability should immediately apply the patches released by GitLab in their subsequent versions, specifically targeting the fixes implemented in GitLab 13.10.2 and later releases. The mitigation strategy should include comprehensive input validation, proper output encoding, and regular security audits of user-contributed content processing pipelines. Additionally, implementing web application firewalls and content security policies can provide additional layers of protection. This vulnerability demonstrates the critical importance of secure coding practices and proper input sanitization in collaborative development platforms, as outlined in the ATT&CK framework's web application attack patterns. Regular security training for developers and implementation of automated security scanning tools can help prevent similar vulnerabilities from emerging in future versions of GitLab and other web applications.