CVE-2021-3904 in grav
Summary
by MITRE • 10/28/2021
grav is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
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Analysis
by VulDB Data Team • 11/01/2021
The grav content management system presents a critical cross-site scripting vulnerability that stems from inadequate input validation during web page generation processes. This vulnerability falls under the CWE-79 category of Improper Neutralization of Input During Web Page Generation, which represents one of the most prevalent and dangerous web application security flaws. The flaw manifests when user-supplied data is not properly sanitized before being rendered in web pages, creating opportunities for malicious actors to inject arbitrary script code that executes in the context of other users' browsers.
The technical implementation of this vulnerability occurs within grav's content rendering pipeline where form inputs, URL parameters, or user-generated content are directly incorporated into HTML output without appropriate encoding or sanitization measures. Attackers can exploit this weakness by submitting malicious payloads through various entry points such as contact forms, comment sections, or URL parameters that are subsequently displayed on web pages. The XSS vulnerability enables threat actors to execute scripts in victims' browsers, potentially leading to session hijacking, credential theft, or redirection to malicious sites.
The operational impact of this vulnerability extends beyond simple script execution, as it can be leveraged for more sophisticated attacks within the context of the ATT&CK framework's initial access and execution phases. Successful exploitation allows attackers to manipulate user sessions, steal authentication tokens, or perform actions on behalf of authenticated users. The vulnerability affects grav's core functionality where user input is processed and rendered, making it particularly dangerous as it can be triggered through multiple vectors including administrative interfaces and public-facing forms.
Mitigation strategies for this vulnerability involve implementing comprehensive input sanitization and output encoding mechanisms throughout the application's data flow. Organizations should deploy proper HTML escaping routines for all user-supplied content before rendering, implement Content Security Policy headers to restrict script execution, and utilize secure coding practices that follow OWASP's XSS prevention guidelines. Regular security updates and patch management procedures are essential as this vulnerability has been addressed in subsequent versions of the grav platform, making immediate remediation crucial for maintaining application security posture.