CVE-2025-13471 is a vulnerability in the User Activity Log WordPress plugin (versions through 2.2) that allows unauthenticated attackers to bypass authorization controls by exploiting improper handling of failed login attempts. The root cause is linked to CWE-639, which describes authorization bypass through user-controlled keys. In this case, the plugin fails to properly validate or restrict changes to certain options when login attempts fail, enabling attackers to set arbitrary options to 1. For example, an attacker can enable User Registration even if the site administrator has disabled it, potentially allowing unauthorized account creation. This can lead to further exploitation such as privilege escalation, spam account creation, or unauthorized access to site resources. The vulnerability does not require authentication or user interaction, increasing its risk profile. Although no public exploits are currently known, the flaw is significant due to the widespread use of WordPress and the plugin’s role in managing user activity and site options. The lack of a patch at the time of disclosure means affected sites remain vulnerable until updates or mitigations are applied. The vulnerability impacts the confidentiality, integrity, and availability of affected WordPress sites by undermining access controls and site configuration integrity.

For European organizations, this vulnerability poses a significant risk to websites running WordPress with the User Activity Log plugin. Unauthorized enabling of user registration can lead to mass creation of unauthorized accounts, increasing the risk of spam, fraud, or further attacks leveraging compromised or malicious accounts. Public sector websites, e-commerce platforms, and membership-based services are particularly vulnerable as they often rely on controlled user registration to maintain security and compliance with data protection regulations such as GDPR. The integrity of site configurations can be compromised, potentially leading to broader security incidents or reputational damage. Additionally, unauthorized changes to site options can disrupt normal operations and availability. The vulnerability’s exploitation does not require authentication, making it easier for attackers to target European organizations with public-facing WordPress sites. The impact is amplified in sectors with strict regulatory requirements and high-value data, such as finance, healthcare, and government services.

Immediate mitigation steps include restricting access to the WordPress admin interface and plugin settings through IP whitelisting or VPN access to reduce exposure. Administrators should monitor changes to critical options, especially those controlling user registration and authentication settings, using file integrity monitoring or WordPress activity logs. Until an official patch is released, consider disabling or uninstalling the User Activity Log plugin if feasible. Employ web application firewalls (WAFs) with custom rules to detect and block suspicious requests attempting to modify plugin options without proper authentication. Regularly audit user accounts and registrations to identify and remove unauthorized accounts promptly. Educate site administrators on the risks and signs of exploitation. Once a patch is available, prioritize updating the plugin to the latest secure version. Additionally, implement multi-factor authentication for administrative accounts to reduce the risk of privilege escalation from compromised accounts.