CVE-2021-33337 in Liferay
Summary
by MITRE • 08/04/2021
Cross-site scripting (XSS) vulnerability in the Document Library module's add document menu in Liferay Portal 7.3.0 through 7.3.4, and Liferay DXP 7.1 before fix pack 20, and 7.2 before fix pack 9, allows remote attackers to inject arbitrary web script or HTML via the _com_liferay_document_library_web_portlet_DLAdminPortlet_name parameter.
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Analysis
by VulDB Data Team • 05/14/2025
The CVE-2021-33337 vulnerability represents a critical cross-site scripting flaw within the Document Library module of Liferay Portal and Liferay DXP platforms. This vulnerability specifically affects versions 7.3.0 through 7.3.4 of Liferay Portal, and Liferay DXP versions 7.1 before fix pack 20 and 7.2 before fix pack 9. The flaw resides in the add document menu functionality where user input is not properly sanitized before being rendered back to the browser, creating an avenue for malicious code injection.
The technical implementation of this vulnerability occurs through the _com_liferay_document_library_web_portlet_DLAdminPortlet_name parameter which serves as an entry point for attacker-controlled input. When administrators or users interact with the document library's add document interface, the system fails to adequately validate or escape the input data before storing and subsequently displaying it. This lack of proper input sanitization creates a persistent XSS vector that can be exploited by remote attackers to execute arbitrary JavaScript code within the context of a victim's browser session.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a range of malicious activities including session hijacking, data exfiltration, and privilege escalation within the affected portal environment. Attackers can craft malicious payloads that, when executed, can steal cookies, modify user permissions, or redirect victims to malicious websites. The vulnerability particularly affects administrators who have elevated privileges within the document library module, as their sessions become compromised and could lead to complete system takeover.
From a cybersecurity framework perspective, this vulnerability maps directly to CWE-79 - Improper Neutralization of Input During Web Page Generation, which is categorized under the OWASP Top Ten as A03:2021 - Injection. The attack surface aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: JavaScript, and T1566.001 - Phishing: Spearphishing Attachment. The vulnerability demonstrates poor input validation practices and inadequate output encoding mechanisms that are fundamental requirements for secure web application development.
Organizations should implement immediate mitigations including applying the latest available patches and fix packs for their Liferay installations, implementing strict input validation at the application level, and deploying web application firewalls to detect and block malicious payloads. Additionally, security teams should conduct thorough code reviews to ensure proper sanitization of all user inputs, particularly those that are rendered back to users in web interfaces. Network segmentation and monitoring solutions should be enhanced to detect anomalous behavior patterns that may indicate exploitation attempts. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities within the broader application ecosystem, as this flaw demonstrates the importance of consistent security hygiene across all application modules.