CVE-2025-11167 identifies an open redirect vulnerability in the CM Registration – Tailored tool for seamless login and invitation-based registrations WordPress plugin, affecting all versions up to and including 2.5.6. The root cause is insufficient validation of the 'redirect_url' parameter, which attackers can manipulate to redirect users to arbitrary, potentially malicious external websites. This vulnerability does not require authentication but does require user interaction, such as clicking on a maliciously crafted URL. The vulnerability is categorized under CWE-601 (URL Redirection to Untrusted Site). The CVSS v3.1 base score is 4.7 (medium), reflecting network attack vector, low attack complexity, no privileges required, but user interaction needed, and a scope change due to the redirect affecting user sessions. While the vulnerability does not directly compromise confidentiality or availability, it can facilitate phishing, credential theft, or malware delivery by redirecting users to attacker-controlled sites. No public exploits have been reported to date, but the risk remains significant due to the widespread use of WordPress and this plugin for user registration workflows. The vulnerability is particularly concerning in environments where users trust the domain and may not suspect redirection to malicious sites. The lack of a patch link indicates that a fix may not yet be publicly available, increasing the urgency for mitigation steps.

For European organizations, this vulnerability poses a moderate risk primarily through social engineering and phishing attacks. Attackers can exploit the open redirect to lure users into malicious sites that may harvest credentials, distribute malware, or conduct further attacks. Organizations that rely on the CM Registration plugin for user onboarding or invitation-based workflows could see reputational damage if users are compromised via these redirects. The vulnerability does not directly impact data confidentiality or system integrity but can be a stepping stone for more severe attacks. Given the extensive use of WordPress across Europe, especially in small to medium enterprises and public sector websites, the potential attack surface is significant. The impact is heightened in sectors with sensitive user data or critical services, such as finance, healthcare, and government. Additionally, phishing attacks leveraging this vulnerability could undermine trust in digital services and complicate compliance with GDPR requirements related to user data protection and incident response.

European organizations should implement the following specific mitigations: 1) Immediately audit all instances of the CM Registration plugin and identify versions up to 2.5.6 in use. 2) Apply any available patches or updates from the vendor as soon as they are released; if no patch is available, consider disabling or replacing the plugin temporarily. 3) Implement strict server-side validation of the 'redirect_url' parameter to allow only whitelisted internal URLs or domains under organizational control. 4) Employ web application firewalls (WAFs) with rules to detect and block suspicious redirect patterns or parameters. 5) Educate users and administrators about the risks of clicking on unexpected links, especially those involving login or registration workflows. 6) Monitor web traffic and logs for unusual redirect attempts or spikes in user complaints related to phishing. 7) Consider multi-factor authentication (MFA) for user logins to reduce the impact of credential theft resulting from phishing. 8) Review and enhance incident response plans to quickly address phishing campaigns leveraging this vulnerability. 9) Engage with the plugin vendor and WordPress security communities to track patch releases and threat intelligence updates.