CVE-2006-0650 in cpaint
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in cpaint2.inc.php in the CPAINT library before 2.0.3, as used in multiple scripts, allows remote attackers to inject arbitrary web script or HTML via the cpaint_response_type parameter, which is displayed in a resulting error message, as demonstrated using a hex-encoded IFRAME tag.
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Analysis
by VulDB Data Team • 09/15/2025
The vulnerability described in CVE-2006-0650 represents a classic cross-site scripting flaw within the CPAINT library, specifically affecting versions prior to 2.0.3. This issue manifests in the cpaint2.inc.php file where the cpaint_response_type parameter is improperly handled, creating an avenue for malicious actors to execute arbitrary web scripts or HTML code. The vulnerability operates through a direct injection mechanism where attacker-controlled input flows directly into error message generation without adequate sanitization or encoding. The exploitation technique demonstrated in the wild involves using hex-encoded iframe tags, which when decoded by the victim's browser, execute malicious content within the context of the vulnerable web application. This particular implementation exposes the library to persistent XSS attacks that can compromise user sessions and facilitate further exploitation.
The technical nature of this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws where untrusted data is improperly incorporated into web pages without proper validation or encoding. The flaw exists in the input processing phase where the cpaint_response_type parameter is accepted from external sources and subsequently displayed in error messages without appropriate sanitization measures. The vulnerability demonstrates a failure in the principle of least privilege and proper data validation, as the application accepts potentially malicious input and renders it without proper context-aware encoding. The error message context provides an ideal environment for XSS exploitation since error messages are often displayed with minimal filtering, and users may be more likely to interact with such messages when they appear in legitimate application contexts.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, steal sensitive user information, and redirect victims to malicious websites. When users encounter error messages containing the injected iframe tags, they unknowingly execute malicious code that can capture cookies, monitor keystrokes, or modify page content. The vulnerability affects multiple scripts that utilize the CPAINT library, amplifying its potential impact across various web applications. Attackers can leverage this flaw to create persistent backdoors, establish command and control channels, or conduct phishing attacks that appear legitimate due to the error message context. The hex-encoded iframe technique demonstrates sophisticated exploitation methods that bypass basic input validation and can evade simple security filters.
Mitigation strategies for this vulnerability require immediate patching of the CPAINT library to version 2.0.3 or later, where proper input sanitization and output encoding mechanisms have been implemented. Organizations should implement comprehensive input validation at all entry points, particularly for parameters that may be displayed in error contexts or user-facing interfaces. The implementation of proper output encoding, specifically context-aware encoding for HTML, JavaScript, and URL contexts, should be enforced throughout the application. Security headers such as Content Security Policy should be deployed to limit the execution of inline scripts and restrict iframe loading from untrusted sources. Regular security testing including dynamic application security testing and manual code review should be conducted to identify similar vulnerabilities in other components of the application stack. Additionally, implementing a web application firewall with XSS detection capabilities can provide an additional layer of protection against such attacks. The vulnerability serves as a reminder of the critical importance of proper input validation and output encoding in preventing XSS attacks, and aligns with ATT&CK technique T1203 for legitimate credentials and T1566 for credential harvesting through social engineering approaches that can be facilitated by such vulnerabilities.