CVE-2025-15708 in Live Composer Plugin
Summary
by MITRE • 11/07/2026
The Live Composer WordPress plugin before 2.1.23 does not sanitise and escape some of its custom post type slug settings before using them in front-end links, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in a multisite setup).
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Analysis
by VulDB Data Team • 11/07/2026
The vulnerability identified in Live Composer WordPress plugin versions prior to 2.1.23 represents a significant security flaw rooted in improper input validation and output encoding mechanisms. Specifically, the application fails to properly sanitize or escape custom post type slug settings before incorporating them into front-end hyperlinks. This oversight creates an avenue for Stored Cross-Site Scripting attacks, which are particularly dangerous because the malicious payload is persisted on the server rather than being delivered via a transient link in a phishing email or similar vector. The persistence of this code means that every time a user visits a page containing the affected slug, the injected script executes within their browser session, potentially leading to account hijacking, data theft, or defacement depending on the victim's privileges and the context of execution.
From a technical perspective, the core issue lies in the handling of custom post type slugs. When an administrator configures these settings, the input is accepted without sufficient validation against malicious script injection patterns. Subsequently, when the plugin generates front-end links using this data, it fails to apply appropriate output encoding functions such as esc_url or similar sanitization routines mandated by WordPress coding standards. This lack of escaping allows arbitrary JavaScript code to be embedded directly into the HTML structure of the page. The severity is compounded by the fact that this vulnerability affects high-privilege users like administrators. In many security models, it is assumed that administrative actions are safe because only trusted individuals have access; however, if an administrator account is compromised through other means such as credential stuffing or phishing, this stored XSS can be leveraged to escalate privileges further or spread malware across the network by exploiting the trust relationship between the admin and their visitors.
The operational impact of this vulnerability extends beyond simple script execution. In a multisite WordPress setup where the unfiltered_html capability is explicitly disabled for administrators to prevent direct HTML injection, this specific flaw bypasses those restrictions because it exploits the handling of post type slugs rather than content fields typically governed by that capability. This means that even in hardened environments designed to mitigate common XSS vectors, attackers can still inject and execute malicious scripts. The consequences include potential session hijacking where attacker-controlled cookies are stolen, allowing full takeover of the administrator's session. Additionally, if the site serves public-facing content, visitors may also be targeted, leading to broader compromise scenarios including redirection to phishing sites or installation of browser-based malware.
To mitigate this risk, immediate action is required by upgrading the Live Composer plugin to version 2.1.23 or later where these input validation and output encoding issues have been addressed. Developers should ensure that all user-supplied data used in URL construction undergoes rigorous sanitization using functions like sanitize_text_field before storage and proper escaping with esc_url when rendered in HTML contexts. Adhering strictly to the WordPress Coding Standards for security is essential to prevent such flaws. Furthermore, implementing a Content Security Policy can provide an additional layer of defense by restricting the sources from which scripts are allowed to load or execute, thereby limiting the impact even if a vulnerability exists. Regular auditing of plugin code against CWE-79 Improper Neutralization of Input During Web Page Generation and alignment with MITRE ATT&CK techniques such as T1059 Command and Scripting Interpreter can help identify similar weaknesses in other components of the web application stack.