CVE-2021-42946 in htmly
Summary
by MITRE • 03/31/2022
A Cross Site Scripting (XSS) vulnerability exists in htmly.2.8.1 via the Copyright field in the /admin/config page.
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Analysis
by VulDB Data Team • 04/05/2022
The vulnerability identified as CVE-2021-42946 represents a critical cross site scripting flaw within the htmly content management system version 2.8.1. This vulnerability specifically targets the administrative configuration interface where users can manage copyright information through the Copyright field input. The issue arises from inadequate input validation and output sanitization mechanisms that fail to properly escape or filter malicious script content entered by attackers. The vulnerability exists in the administrative context at the /admin/config page, making it particularly dangerous as it provides attackers with access to privileged administrative functions.
The technical exploitation of this vulnerability occurs when an attacker injects malicious javascript code into the Copyright field through the administrative interface. When the compromised page is rendered, the injected script executes within the context of other users' browsers who visit the affected administrative pages. This creates a persistent cross site scripting condition where the malicious payload can capture user sessions, steal sensitive information, or redirect users to malicious websites. The vulnerability stems from the application's failure to properly sanitize user input before rendering it back to the browser, creating an attack surface that aligns with CWE-79 - Improper Neutralization of Input During Web Page Generation. The flaw demonstrates poor input validation practices that violate secure coding principles established in the OWASP Top Ten and the CWE hierarchy.
The operational impact of this vulnerability extends beyond simple script injection as it compromises the integrity of the entire administrative interface. Attackers can leverage this vulnerability to escalate privileges, modify content, or gain unauthorized access to sensitive system configurations. The administrative context of the vulnerability means that successful exploitation could lead to complete system compromise, as attackers would have access to all administrative functions and potentially sensitive data. This vulnerability aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: JavaScript, and represents a significant threat to the confidentiality, integrity, and availability of the affected system. The persistent nature of the XSS vulnerability means that once exploited, the malicious code can continue to affect users until the input field is properly sanitized and the vulnerability is patched.
Mitigation strategies for CVE-2021-42946 must focus on implementing robust input validation and output encoding mechanisms throughout the application's administrative interface. The primary remediation involves sanitizing all user inputs, particularly those rendered in administrative contexts, through proper HTML entity encoding and input validation routines. Organizations should implement Content Security Policy headers to prevent execution of unauthorized scripts and ensure that all administrative pages properly escape dynamic content. The fix should include comprehensive input validation that rejects or sanitizes potentially malicious content before storage and rendering. Additionally, regular security testing including automated vulnerability scanning and manual penetration testing should be conducted to identify similar issues in other input fields. The remediation process should follow the OWASP Secure Coding Practices guidelines and the CWE remediation strategies for preventing cross site scripting vulnerabilities. Regular patch management procedures should be implemented to ensure timely deployment of security updates and prevent similar vulnerabilities from persisting in the application's codebase.