CVE-2015-3429 in Genericons
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in example.html in Genericons before 3.3.1, as used in WordPress before 4.2.2, allows remote attackers to inject arbitrary web script or HTML via a fragment identifier.
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Analysis
by VulDB Data Team • 05/21/2022
The vulnerability described in CVE-2015-3429 represents a cross-site scripting flaw that emerged in the Genericons library, a popular icon font package used extensively within the WordPress ecosystem. This particular weakness was present in Genericons versions prior to 3.3.1 and affected WordPress installations before version 4.2.2, creating a significant security risk for millions of websites that relied on these icon libraries. The vulnerability specifically targeted the example.html file within the Genericons package, which served as a demonstration interface for developers and users to preview available icons. The flaw was particularly concerning because it allowed remote attackers to execute malicious scripts in the context of a victim's browser, potentially leading to unauthorized actions on behalf of the user.
The technical nature of this vulnerability stems from insufficient input validation and output encoding within the example.html file. When users interacted with the demonstration interface, the fragment identifier portion of the URL was not properly sanitized before being rendered in the browser. This weakness enabled attackers to inject malicious JavaScript code through the URL fragment, which would then execute in the context of the victim's browser session. The vulnerability falls under CWE-79, which specifically addresses Cross-Site Scripting flaws, and aligns with the ATT&CK technique T1059.001 for command and scripting interpreter. The fragment identifier injection technique exploits the fact that browsers process URL fragments without sending them to the server, making traditional server-side input sanitization ineffective against this particular attack vector.
The operational impact of CVE-2015-3429 was substantial across the WordPress community, as the Genericons library was widely integrated into various themes and plugins. Attackers could craft malicious URLs that, when clicked by unsuspecting users, would execute arbitrary scripts in their browsers. This could lead to session hijacking, data theft, defacement of websites, or redirection to malicious sites. The vulnerability was particularly dangerous because it required minimal user interaction beyond clicking a link, making it an effective vector for social engineering attacks. The widespread adoption of Genericons meant that countless WordPress installations were potentially exposed, creating a significant attack surface that could be exploited across different website types and user bases.
Mitigation strategies for this vulnerability required immediate updates to both the Genericons library and WordPress core installations. Users were advised to upgrade to Genericons 3.3.1 or later versions, while WordPress installations needed to be updated to version 4.2.2 or higher to receive the necessary patches. Security administrators should have implemented additional monitoring of user-generated content and URL parameters to detect potential exploitation attempts. The fix involved proper sanitization of fragment identifiers before rendering them in the browser context, ensuring that any potentially malicious input was neutralized before execution. Organizations should have also considered implementing content security policies to limit the execution of inline scripts and reduce the overall impact of potential XSS vulnerabilities. This vulnerability highlighted the importance of maintaining updated third-party libraries and the critical need for comprehensive security testing across all components of web applications.