CVE-2020-13328 in GitLab
Summary
by MITRE
An issue has been discovered in GitLab affecting versions prior to 13.1.2, 13.0.8 and 12.10.13. GitLab was vulnerable to a stored XSS by using the PyPi files API.
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Analysis
by VulDB Data Team • 11/15/2020
The vulnerability identified as CVE-2020-13328 represents a critical stored cross-site scripting flaw within GitLab's PyPi files API functionality. This security weakness affects multiple versions of the GitLab platform including those prior to 13.1.2, 13.0.8, and 12.10.13, exposing organizations to persistent XSS attacks through the package management interface. The vulnerability specifically resides in how GitLab processes and stores PyPi package metadata, creating an attack vector where malicious actors can inject malicious scripts into package descriptions, titles, or other user-provided content that gets rendered in the web interface.
The technical flaw stems from insufficient input validation and output sanitization within GitLab's PyPi integration module. When users upload or modify PyPi packages through the API, the system fails to properly sanitize user-supplied content before storing it in the database. This stored data is then subsequently rendered in web pages without adequate escaping or encoding, allowing malicious JavaScript code to execute in the context of other users' browsers. The vulnerability is classified as a stored XSS attack under CWE-79, which specifically addresses improper neutralization of input during web page generation in web applications.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform a range of malicious activities including session hijacking, credential theft, and data exfiltration from authenticated GitLab users. An attacker who successfully exploits this vulnerability could potentially gain access to private repositories, modify code, manipulate project data, or even escalate privileges within the GitLab environment. The persistent nature of stored XSS means that once the malicious payload is injected, it will continue to execute for all users who view the affected package details until the vulnerability is patched and the malicious content is removed from the system.
Organizations utilizing GitLab versions affected by CVE-2020-13328 should immediately implement mitigations including applying the relevant security patches released by GitLab, which address the input validation issues in the PyPi files API. Additionally, administrators should consider implementing web application firewalls to monitor for suspicious API requests and enhance their monitoring capabilities for anomalous package upload activities. The ATT&CK framework categorizes this vulnerability under T1566.001 - Phishing: Spearphishing Attachment, as attackers could leverage this vulnerability to deliver malicious payloads through package repositories. Regular security audits of API endpoints and input validation mechanisms should be conducted to prevent similar issues, while implementing proper content security policies and output encoding practices to prevent XSS vulnerabilities in web applications.