CVE-2013-6780 in cPanel WHM
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in uploader.swf in the Uploader component in Yahoo! YUI 2.5.0 through 2.9.0 allows remote attackers to inject arbitrary web script or HTML via the allowedDomain parameter.
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Analysis
by VulDB Data Team • 06/04/2021
The CVE-2013-6780 vulnerability represents a critical cross-site scripting flaw within the Yahoo! YUI Uploader component that affects versions 2.5.0 through 2.9.0. This vulnerability resides in the uploader.swf flash file and specifically targets the allowedDomain parameter, which serves as an entry point for malicious code injection. The flaw demonstrates a classic XSS vulnerability pattern where untrusted input is directly incorporated into web pages without proper sanitization or encoding mechanisms.
The technical exploitation of this vulnerability occurs through the manipulation of the allowedDomain parameter within the flash-based uploader component. When an attacker crafts malicious input containing script tags or HTML content and passes it through this parameter, the flash application fails to properly validate or sanitize the input before rendering it within the web page context. This allows attackers to inject arbitrary web scripts that execute in the context of the victim's browser session, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The vulnerability specifically aligns with CWE-79 which catalogs improper neutralization of input during web page generation, and represents a direct violation of secure coding practices for input validation and output encoding.
The operational impact of this vulnerability extends beyond simple script injection as it provides attackers with a persistent means of compromising user sessions within applications that utilize the affected YUI components. Since the vulnerability exists in a widely used JavaScript library, the potential attack surface is extensive across numerous web applications that depend on Yahoo! YUI for their uploader functionality. The flash-based nature of the vulnerability also introduces additional complexity as it operates outside traditional browser sandboxing mechanisms, potentially allowing for more sophisticated attack vectors. This flaw particularly affects web applications that implement flash-based file upload capabilities and rely on the YUI library for user interface components, creating a significant risk for organizations with legacy systems still utilizing these vulnerable versions.
Organizations should immediately implement mitigations including updating to patched versions of the YUI library, implementing strict input validation for all parameters passed to flash components, and applying content security policies that restrict script execution within affected applications. The remediation process must include thorough code auditing to identify all instances where the vulnerable Uploader component is utilized, followed by comprehensive testing to ensure that the patch does not introduce regressions in functionality. Security teams should also consider implementing web application firewalls that can detect and block malicious payloads targeting this specific vulnerability pattern, and establish monitoring procedures to detect potential exploitation attempts. This vulnerability serves as a reminder of the critical importance of maintaining up-to-date third-party libraries and the risks associated with legacy components that may contain undiscovered security flaws, particularly those involving client-side technologies like flash that have historically been prone to such vulnerabilities.