CVE-2020-13331 in GitLab
Summary
by MITRE
An issue has been discovered in GitLab affecting versions prior to 12.10.13. GitLab was vulnerable to a stored XSS by in the Wiki pasges.
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Analysis
by VulDB Data Team • 11/15/2020
The vulnerability identified as CVE-2020-13331 represents a critical stored cross-site scripting flaw within GitLab's wiki functionality that affected versions prior to 12.10.13. This security weakness allowed attackers to inject malicious scripts into wiki pages that would persist and execute when other users viewed these pages, creating a significant risk for organizations relying on GitLab's collaborative documentation features. The vulnerability specifically targeted the wiki page rendering mechanism where user input was not properly sanitized before being displayed to other users, enabling attackers to exploit this weakness through crafted malicious content that could be stored within the wiki system.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within GitLab's wiki rendering pipeline. When users created or edited wiki pages, the system failed to adequately sanitize user-provided content before storing and subsequently displaying it to other users. This flaw aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities, and demonstrates how improper sanitization of user input can lead to persistent malicious code execution. The vulnerability exploited the trust relationship between the GitLab application and its users, allowing attackers to inject scripts that would execute in the context of other users' browsers when they accessed affected wiki pages, potentially leading to session hijacking, data theft, or further exploitation of the compromised user accounts.
The operational impact of this stored XSS vulnerability extends beyond simple script execution, as it could enable attackers to escalate privileges and access sensitive project information or manipulate collaborative documentation. Organizations using GitLab for internal knowledge sharing, technical documentation, or collaborative development would face significant risk if attackers successfully exploited this vulnerability, as wiki pages often contain sensitive information about project structures, development processes, or security configurations. The persistent nature of stored XSS makes this vulnerability particularly dangerous because once injected, the malicious scripts would execute automatically each time affected users accessed the compromised wiki pages, potentially affecting numerous users within an organization and creating a wide attack surface that could be leveraged for further compromise.
Mitigation strategies for CVE-2020-13331 primarily involve upgrading to GitLab version 12.10.13 or later, which includes proper input sanitization and output encoding fixes for wiki page rendering. Organizations should also implement additional security measures such as content security policies to limit script execution, regular security scanning of wiki content, and user education regarding the risks of viewing untrusted wiki pages. The fix addresses the root cause by implementing proper HTML escaping and input validation mechanisms that prevent malicious scripts from being stored and executed within the wiki system, aligning with ATT&CK technique T1213 which covers data from information repositories. Security teams should also conduct thorough audits of existing wiki content to identify any previously injected malicious scripts and ensure that all users have been migrated to secure versions of the platform to prevent exploitation of this vulnerability.