CVE-2012-4000 in FCKeditor
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the print_textinputs_var function in editor/dialog/fck_spellerpages/spellerpages/server-scripts/spellchecker.php in FCKeditor 2.6.7 and earlier allows remote attackers to inject arbitrary web script or HTML via textinputs array parameters.
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Analysis
by VulDB Data Team • 01/10/2025
The CVE-2012-4000 vulnerability represents a critical cross-site scripting flaw within FCKeditor version 2.6.7 and earlier, specifically affecting the print_textinputs_var function located in the spellchecker.php file. This vulnerability resides within the server-side script that handles spell checking functionality for the rich text editor, making it particularly dangerous as it operates in the context of web applications that utilize FCKeditor for content management. The flaw stems from inadequate input validation and sanitization of user-supplied parameters, specifically the textinputs array variables that are processed by the spellchecker component.
The technical implementation of this vulnerability occurs when the print_textinputs_var function fails to properly escape or sanitize input data before rendering it within the web page context. Attackers can exploit this weakness by crafting malicious payloads within the textinputs array parameters that contain script tags or other HTML content. When the vulnerable spellchecker processes these inputs and subsequently renders them back to the browser, the malicious code executes within the context of the victim's session, potentially leading to session hijacking, data theft, or unauthorized actions performed on behalf of the user. This vulnerability is classified as a classic reflected XSS attack pattern, where malicious input is immediately reflected back to the user without proper sanitization.
The operational impact of CVE-2012-4000 extends beyond simple script execution as it fundamentally undermines the security boundaries of web applications that depend on FCKeditor for content management. Attackers can leverage this vulnerability to steal session cookies, redirect users to malicious websites, inject malicious content into web pages, or perform actions that appear to originate from legitimate users within the application. The vulnerability is particularly concerning because FCKeditor was widely deployed in content management systems, web applications, and enterprise platforms, meaning that exploitation could potentially compromise numerous web applications simultaneously. This flaw directly violates security principles outlined in CWE-79, which addresses cross-site scripting vulnerabilities, and aligns with ATT&CK technique T1566.001 for initial access through spearphishing attachments, as attackers could use this vulnerability to deliver malicious payloads through compromised web applications.
Organizations utilizing affected versions of FCKeditor should implement immediate mitigations including upgrading to a patched version of the editor, implementing proper input validation and output encoding for all user-supplied data, and deploying web application firewalls to detect and block malicious payloads. The vulnerability demonstrates the critical importance of input sanitization in web applications and highlights the necessity of following secure coding practices as outlined in OWASP Top Ten and NIST Cybersecurity Framework guidelines. Additionally, regular security assessments and dependency updates should be implemented to prevent similar vulnerabilities from being introduced through legacy components in web applications.