CVE-2012-2914 in captcha
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in captchademo.php in Unijimpe Captcha allows remote attackers to inject arbitrary web script or HTML via the PATH_INFO.
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Analysis
by VulDB Data Team • 05/15/2025
The CVE-2012-2914 vulnerability represents a critical cross-site scripting flaw in the Unijimpe Captcha plugin's captchademo.php component. This vulnerability exists within the web application's input validation mechanisms, specifically failing to properly sanitize user-supplied data that flows through the PATH_INFO server variable. The issue stems from the application's inability to adequately filter or escape special characters in the URL path information, creating an exploitable vector for malicious code injection. Attackers can leverage this weakness by crafting malicious URLs containing script tags or other HTML content within the PATH_INFO parameter, which then gets rendered in the web page without proper sanitization.
The technical implementation of this vulnerability aligns with CWE-79 which defines Cross-Site Scripting as a security weakness where untrusted data is sent to a web browser without proper validation or escaping. The flaw specifically manifests when the captchademo.php script processes the PATH_INFO variable without implementing appropriate output encoding or input validation controls. This allows threat actors to inject malicious JavaScript code or HTML content that executes in the context of other users' browsers who visit the affected page. The vulnerability is particularly concerning because it operates at the application layer, making it accessible through standard web browser interactions without requiring additional authentication or privileged access.
From an operational perspective, this vulnerability poses significant risks to web application security and user privacy. When exploited, the XSS attack can enable session hijacking, credential theft, data exfiltration, and redirection to malicious sites. The impact extends beyond simple script injection as it can facilitate more sophisticated attacks such as credential harvesting through form submissions or browser manipulation techniques. The vulnerability affects any user who visits a page utilizing the compromised captchademo.php script, making it particularly dangerous in environments with high user traffic or where the application handles sensitive information. The attack vector is relatively simple to exploit, requiring only a crafted URL with malicious content in the PATH_INFO parameter, which makes it a popular target for automated attack tools.
Mitigation strategies for CVE-2012-2914 should focus on implementing proper input validation and output encoding mechanisms. The primary solution involves sanitizing all user-supplied data, particularly data derived from PATH_INFO, through proper encoding before rendering in web pages. This approach aligns with the ATT&CK framework's defense evasion techniques and represents a fundamental security practice for preventing XSS vulnerabilities. Organizations should implement Content Security Policy headers to limit script execution, employ proper HTML escaping functions, and ensure all web applications validate and sanitize input parameters. Additionally, the affected Unijimpe Captcha plugin should be updated to a patched version that properly handles the PATH_INFO variable through appropriate sanitization routines. Regular security testing including dynamic application security testing and manual code review should be conducted to identify similar vulnerabilities in other components of the web application stack.