Theme My Login (TML) is a WordPress plugin utilized by website administrators to offer front-end login, registration, and profile functionalities to users. Typically active in multisite WordPress installations, it provides ways to handle user sessions outside the default WordPress login interfaces. This plugin is widely used where customization of user access is necessary without altering the core WordPress features. Businesses and bloggers alike implement this tool to streamline user interaction and maintain a branded user experience on their websites. Offering robust features like custom redirects, Theme My Login empowers site owners to enhance the login process seamlessly. Such versatility makes it a potent asset in the toolkit of any WordPress developer.
A vulnerability in Theme My Login (TML) version 7.2.1 and below allows unauthenticated attackers to escalate privileges on WordPress multisite installations. Exploited via the unprotected tml_ms_filter_pre_insert_user_data() filter, this flaw allows bypassing authentication processes. Intrusions occur when the tml_user_passwords network option is enabled, leading to unauthorized password resets for existing users. This critical flaw, CVE-2026-89079, enables attackers to spoof or reset user credentials without their knowledge. The impact encompasses both regular users and network administrators, seemingly offering attackers full control over a WordPress site. Addressing this vulnerability requires critical security updates and enhanced monitoring mechanisms.
Technically, the vulnerability is activated when an unauthenticated attacker sends a crafted POST request during a lost password process. The filter tml_ms_filter_pre_insert_user_data() intercepts the request and hashes the attacker-provided 'user_pass1' within the user record. It bypasses the $update flag check necessary for legitimate user updates, allowing malicious actors to reset user passwords without authorization. The trigger is embedded in the WordPress function chain - wp-login.php -> retrieve_password() -> wp_update_user(). Fixed by introducing an $update guard, this vulnerability highlights the exigency for robust code reviews and preemptive security patches. Subsequent plugin updates are crucial in mitigating exploitation risks.
When exploited, this vulnerability leads to complete account takeovers, including those of network administrators, potentially compromising the entire WordPress multisite installation. Attackers could alter or delete content, lock owners out of their accounts, and access confidential user information. Such control facilitates further malicious activities, including injecting malware, conducting phishing attacks, or redirecting users to harmful sites. This exposure risks not only the website's integrity but also the privacy and trustworthiness perceived by its user base. It necessitates immediate attention and remediation to prevent financial and reputational losses.
REFERENCES
- https://patchstack.com/database/wordpress/plugin/theme-my-login/vulnerability/wordpress-theme-my-login-plugin-7-2-1-unauthenticated-privilege-escalation-vulnerability
- https://plugins.trac.wordpress.org/changeset/3696081/theme-my-login
- https://github.com/theme-my-login/theme-my-login/commit/06b76231b86150eed932db52646734486ecd0781
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-89079
- Update Theme My Login to version 7.2.2 or newer immediately to patch the vulnerability.
- Temporarily disable the tml_user_passwords option until the plugin is updated.
- Configure WordPress security settings to limit unauthorized access attempts.
- Monitor site access logs regularly to identify suspicious activities targeted at user accounts.
- Educate users on the importance of safeguarding their account credentials.
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