CVE-2006-5239 in eXpBlog
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in eXpBlog 0.3.5 and earlier allow remote attackers to inject arbitrary web script or HTML via (1) the query string (PHP_SELF) in kalender.php or (2) the captcha_session_code parameter in pre_details.php.
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Analysis
by VulDB Data Team • 04/24/2026
The vulnerability identified as CVE-2006-5239 represents a critical cross-site scripting flaw affecting eXpBlog version 0.3.5 and earlier installations. This vulnerability resides within the web application's input validation mechanisms, specifically failing to properly sanitize user-supplied data before incorporating it into dynamically generated web pages. The flaw manifests through two distinct attack vectors that exploit different parameters within the application's PHP scripts, creating multiple entry points for malicious actors to execute unauthorized code within the context of victim browsers.
The technical implementation of this vulnerability stems from improper handling of user input in two separate PHP files within the eXpBlog application. The first vector involves the PHP_SELF parameter within kalender.php, where the application directly incorporates server variables containing user-supplied query string data without adequate sanitization or encoding. The second vector targets the captcha_session_code parameter in pre_details.php, where the application fails to properly validate or escape input from this specific parameter before rendering it in the web response. Both attack paths demonstrate a classic lack of input validation and output encoding practices that are fundamental to preventing XSS attacks according to the CWE-79 standard for Cross-Site Scripting.
From an operational perspective, this vulnerability enables remote attackers to execute arbitrary web scripts or HTML code within the browser context of authenticated users or visitors. An attacker could craft malicious URLs containing script payloads that would execute when victims navigate to affected pages, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The impact extends beyond simple script execution as these vulnerabilities could be leveraged to perform more sophisticated attacks such as cookie theft, defacement of the blog content, or even privilege escalation if the application handles user authentication or administrative functions. The vulnerability affects the entire user base of affected installations, making it particularly dangerous as any visitor could become a victim of these attacks.
The mitigation strategies for this vulnerability require immediate attention through multiple defensive measures. The primary remediation involves implementing proper input validation and output encoding mechanisms throughout the application, specifically ensuring that all user-supplied data is sanitized before being incorporated into web responses. This aligns with the ATT&CK framework's defense in depth principles, particularly focusing on input validation techniques and output encoding as core defensive controls. Organizations should also implement proper parameter validation in both kalender.php and pre_details.php files, ensuring that PHP_SELF and captcha_session_code parameters are properly escaped or validated before processing. Additionally, the application should be upgraded to a patched version of eXpBlog that addresses these specific vulnerabilities, as the original version is no longer maintained and likely contains additional undiscovered security flaws. Security headers such as Content Security Policy should also be implemented to provide additional protection against XSS attacks, following the OWASP secure coding guidelines that emphasize the importance of multiple layers of defense against web application vulnerabilities.