CVE-2011-3865 in Black-LetterHead
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Black-LetterHead theme before 1.6 for WordPress allows remote attackers to inject arbitrary web script or HTML via the PATH_INFO to index.php.
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Analysis
by VulDB Data Team • 02/02/2025
The CVE-2011-3865 vulnerability represents a critical cross-site scripting flaw within the Black-LetterHead WordPress theme, specifically affecting versions prior to 1.6. This vulnerability resides in the theme's handling of user input through the PATH_INFO parameter when processing requests to index.php, creating a persistent security risk for WordPress installations. The flaw demonstrates how theme-level components can introduce significant attack vectors that extend beyond core WordPress functionality, highlighting the importance of thorough security auditing for all installed themes and plugins.
The technical implementation of this vulnerability stems from inadequate input validation and output sanitization within the Black-LetterHead theme's request processing logic. When the system receives a request with PATH_INFO parameters, the theme fails to properly sanitize or escape these inputs before incorporating them into dynamic web content. This allows malicious actors to inject arbitrary JavaScript code or HTML fragments that execute within the context of other users' browsers. The vulnerability operates at the application layer and can be exploited through simple web requests without requiring authentication, making it particularly dangerous in multi-user environments where users may inadvertently trigger the malicious code execution.
From an operational impact perspective, this XSS vulnerability creates multiple attack vectors that can compromise user sessions, steal sensitive information, or redirect users to malicious websites. Attackers can craft malicious URLs that, when visited by unsuspecting users, execute scripts that steal cookies, session tokens, or personal data. The vulnerability affects not only individual users but also administrators who may be logged in when visiting compromised pages. This represents a significant threat to user privacy and system integrity, as the malicious code can persist across multiple sessions and potentially escalate to more severe attacks if combined with other exploitation techniques.
The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and demonstrates characteristics consistent with attack patterns documented in the MITRE ATT&CK framework under the T1566 technique for "Phishing with Spoofed Content". Organizations affected by this vulnerability should immediately implement the recommended patch updates to version 1.6 or later, which includes proper input sanitization and output encoding mechanisms. Additionally, administrators should consider implementing Content Security Policy headers as an additional defense-in-depth measure, while monitoring for any signs of exploitation attempts in web server logs. Regular security audits of installed themes and plugins should be conducted to identify similar vulnerabilities, as this represents a common pattern in web application security where third-party components introduce attack surfaces that may not be adequately protected by core platform security measures.