CVE-2006-0496 in Firefox
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Mozilla 1.7.12 and possibly earlier, Mozilla Firefox 1.0.7 and possibly earlier, and Netscape 8.1 and possibly earlier, allows remote attackers to inject arbitrary web script or HTML via the -moz-binding (Cascading Style Sheets) CSS property, which does not require that the style sheet have the same origin as the web page, as demonstrated by the compromise of a large number of LiveJournal accounts.
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Analysis
by VulDB Data Team • 06/22/2025
This cross-site scripting vulnerability exists in several versions of Mozilla-based browsers including Mozilla 1.7.12, Firefox 1.0.7, and Netscape 8.1, representing a critical security flaw that allows remote attackers to execute malicious scripts within user browsers. The vulnerability specifically exploits the -moz-binding CSS property which enables the binding of external style sheets to web pages without enforcing strict origin policies. This weakness falls under CWE-79, which categorizes cross-site scripting vulnerabilities as a result of improper neutralization of input during web page generation. The flaw allows attackers to inject arbitrary web script or HTML content through CSS properties, bypassing traditional security mechanisms that would normally prevent such cross-origin operations.
The technical exploitation occurs when malicious actors craft specially designed CSS content that leverages the -moz-binding property to reference external resources that can execute scripts within the context of the victim's browser session. This particular vulnerability is significant because it does not require the stylesheet to originate from the same domain as the web page, violating fundamental security principles of same-origin policy enforcement. The attack vector demonstrates how CSS properties can be weaponized to create persistent XSS payloads that can compromise user sessions and execute unauthorized actions. According to ATT&CK framework, this vulnerability maps to T1059.007 for Scripting and T1531 for Account Access, as it enables attackers to gain unauthorized access to user accounts by compromising their browser sessions.
The operational impact of this vulnerability was demonstrated through the compromise of numerous LiveJournal accounts, highlighting the real-world consequences of such flaws in widely used web browsers. Attackers could create malicious style sheets that would be executed when users visited compromised web pages, potentially stealing session cookies, redirecting users to malicious sites, or performing actions on behalf of authenticated users. The vulnerability's exploitation required minimal user interaction beyond visiting a malicious website, making it particularly dangerous for mass deployment attacks. Security researchers noted that the flaw was particularly concerning because it affected multiple browser versions and operating systems, creating a wide attack surface. Organizations and users were forced to urgently update their browser software to mitigate the risk, as the vulnerability allowed for persistent attacks that could remain undetected for extended periods.
The recommended mitigations for this vulnerability include immediate patching of affected browser versions, implementing proper input validation and sanitization of CSS content, and deploying Content Security Policy headers to restrict external resource loading. Browser vendors should enforce stricter origin policies for CSS properties and implement additional security controls to prevent unauthorized binding operations. Organizations should also consider implementing web application firewalls and monitoring for suspicious CSS content in web applications. The incident underscored the importance of comprehensive security testing for web browsers and highlighted the need for robust cross-origin resource sharing policies that prevent malicious scripts from executing in user contexts. This vulnerability serves as a critical example of how seemingly benign CSS features can be exploited to create serious security threats in web environments.