CVE-2026-1426 is a vulnerability classified under CWE-502 (Deserialization of Untrusted Data) affecting the berocket Advanced AJAX Product Filters WordPress plugin versions up to 3.1.9.6. The flaw exists in the shortcode_check function within the Live Composer compatibility layer, where untrusted input is deserialized without proper validation, enabling PHP Object Injection. This vulnerability requires an attacker to have authenticated Author-level or higher privileges on the WordPress site and the Live Composer plugin must be installed and active. The vulnerability itself does not contain a gadget chain (POP chain) necessary for exploitation; thus, it cannot be exploited in isolation. However, if other plugins or themes installed on the site contain gadget chains, an attacker can leverage this vulnerability to perform dangerous actions such as arbitrary code execution, file deletion, or data exfiltration. The CVSS 3.1 score of 8.8 reflects the high impact on confidentiality, integrity, and availability, with network attack vector, low attack complexity, and no user interaction required. No public exploits are known, but the risk is significant due to the potential for chained exploitation. The vulnerability highlights the risks of unsafe deserialization in WordPress plugins, especially when combined with other vulnerable components.

For European organizations, especially those operating e-commerce platforms or content-heavy websites using WordPress, this vulnerability poses a significant risk. If exploited, attackers could gain the ability to execute arbitrary PHP code, leading to full site compromise, data breaches involving customer or business data, defacement, or service disruption. The requirement for Author-level access somewhat limits the attack surface but remains a concern in environments with multiple content creators or insufficient access controls. The dependency on the Live Composer plugin and the presence of gadget chains in other plugins/themes means that organizations with complex WordPress setups are at higher risk. Successful exploitation could lead to regulatory compliance issues under GDPR due to potential data exposure. Additionally, the disruption or compromise of e-commerce sites could result in financial losses and reputational damage. The lack of known exploits in the wild suggests a window for proactive mitigation before widespread attacks occur.

1. Immediately update the Advanced AJAX Product Filters plugin to a version beyond 3.1.9.6 once a patch is released or remove the plugin if not essential. 2. Audit all installed plugins and themes for known gadget chains or unsafe deserialization vulnerabilities, particularly those interacting with Live Composer. 3. Restrict WordPress user roles to the minimum necessary privileges, limiting Author-level access to trusted users only. 4. Disable or remove the Live Composer plugin if it is not required, as its presence is a prerequisite for exploitation. 5. Implement Web Application Firewall (WAF) rules to detect and block suspicious serialized payloads targeting the shortcode_check function. 6. Monitor logs for unusual activity related to plugin usage or deserialization attempts. 7. Employ security plugins that can detect and prevent PHP Object Injection or unsafe deserialization patterns. 8. Regularly back up WordPress sites and test restoration procedures to minimize downtime in case of compromise. 9. Educate site administrators and developers about the risks of unsafe deserialization and the importance of plugin hygiene.