CVE-2013-5099 in Anchor
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in article.php in Anchor CMS 0.9.1, when comments are enabled, allows remote attackers to inject arbitrary web script or HTML via the Name field. NOTE: some sources have reported that comments.php is vulnerable, but certain functions from comments.php are used by article.php.
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Analysis
by VulDB Data Team • 01/01/2025
The vulnerability described in CVE-2013-5099 represents a classic cross-site scripting flaw within Anchor CMS version 0.9.1 that specifically targets the article.php component when comment functionality is enabled. This type of vulnerability falls under the Common Weakness Enumeration category CWE-79, which defines improper neutralization of input during web page generation as a critical weakness. The vulnerability manifests when users submit comments through the Name field, which is then processed and displayed on the article page without adequate sanitization or encoding of user-supplied input. Attackers can exploit this weakness by crafting malicious payloads within the Name field that, when rendered on the page, execute arbitrary scripts in the context of other users' browsers.
The technical exploitation of this vulnerability occurs because the application fails to properly validate and sanitize user input before rendering it in the web page context. When comments are enabled, the Name field becomes part of the dynamic content generation process, and the application does not implement proper output encoding or input validation mechanisms to prevent malicious scripts from being executed. The attack vector specifically targets the article.php script which incorporates data from comments.php, making the vulnerability particularly dangerous as it affects the core content rendering functionality of the CMS. This creates a persistent threat where any user viewing the affected article page becomes a potential victim of the stored XSS attack.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it enables attackers to establish persistent malicious presence within the CMS environment. Once exploited, attackers can steal session cookies, redirect users to malicious sites, inject malicious advertisements, or even perform actions on behalf of legitimate users if they have administrative privileges. The vulnerability affects all users who view articles with comments enabled, making it a widespread concern that can impact the entire user base of the CMS. From an attacker's perspective, this vulnerability provides a stable and reliable method for conducting long-term campaigns against the target organization's web presence.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and output encoding mechanisms throughout the CMS. The recommended approach includes implementing strict sanitization of all user input fields, particularly those that appear in rendered content, and applying proper HTML encoding before displaying any user-supplied data. Organizations should also consider implementing Content Security Policy (CSP) headers to limit the execution of inline scripts and reduce the impact of successful XSS attacks. The fix should involve updating the Anchor CMS to a patched version that properly handles comment data validation and encoding, while also reviewing all other components that may be vulnerable to similar input handling issues. Additionally, security monitoring should be enhanced to detect unusual patterns in comment submissions that may indicate attempted exploitation of this vulnerability.