CVE-2015-9361 in Related Posts
Summary
by MITRE
The Related Posts plugin before 1.8.2 for WordPress has XSS via add_query_arg() and remove_query_arg().
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Analysis
by VulDB Data Team • 12/07/2023
The CVE-2015-9361 vulnerability affects the Related Posts plugin for WordPress versions prior to 1.8.2, presenting a cross-site scripting flaw that exploits improper input sanitization within the plugin's handling of URL parameters. This vulnerability specifically targets the add_query_arg() and remove_query_arg() functions which are commonly used in WordPress for manipulating query strings in URLs. The flaw arises when user-supplied input is not properly escaped or validated before being incorporated into dynamic URLs that are subsequently rendered in web pages, creating an avenue for malicious actors to inject arbitrary JavaScript code.
The technical implementation of this vulnerability stems from the plugin's failure to adequately sanitize user-controllable parameters that are passed through WordPress's query argument handling functions. When these functions process URL parameters containing malicious payloads, the unsanitized input gets embedded into HTML output without proper encoding or escaping mechanisms. This creates a classic XSS vector where attackers can craft specially formatted URLs that, when visited by unsuspecting users, execute malicious scripts in the context of the victim's browser session. The vulnerability operates at the application layer and can be exploited through various attack vectors including phishing emails, compromised websites, or social engineering campaigns.
The operational impact of CVE-2015-9361 extends beyond simple script execution as it can enable attackers to perform session hijacking, steal cookies, redirect users to malicious sites, or even modify content displayed on the affected WordPress installation. Given that the Related Posts plugin is widely used across WordPress installations, the potential attack surface is substantial, particularly in environments where administrators may not be immediately aware of the vulnerability or have not updated to the patched version. The vulnerability represents a critical security risk that aligns with CWE-79, which categorizes cross-site scripting flaws as a fundamental weakness in web application security.
Mitigation strategies for this vulnerability require immediate patching to version 1.8.2 or later of the Related Posts plugin, as this update addresses the input sanitization issues within the add_query_arg() and remove_query_arg() function calls. Additionally, administrators should implement proper output encoding practices throughout their WordPress installations, particularly when handling user-supplied data in URL parameters. Network security controls such as web application firewalls can provide additional defense-in-depth by monitoring for suspicious query parameter patterns, though these should not be relied upon as the sole protection mechanism. Regular security audits and vulnerability assessments should be conducted to identify similar issues in other plugins and themes, as this vulnerability demonstrates the importance of proper input validation and output encoding in preventing XSS attacks. The ATT&CK framework categorizes this vulnerability under T1213 - Data from Information Repositories, where attackers can leverage such flaws to access sensitive user information and manipulate web content through the exploitation of client-side vulnerabilities.