CVE-2025-9887 is a Cross-Site Request Forgery (CSRF) vulnerability affecting the Custom Login And Signup Widget plugin for WordPress, developed by bittokazi. This vulnerability exists in all versions up to and including 1.0 due to missing or incorrect nonce validation in the /frndzk_adminclsw.php file. Nonces are security tokens used to verify that requests originate from legitimate users and not from malicious third parties. The absence or improper implementation of nonce validation allows an unauthenticated attacker to craft a malicious request that, if executed by a site administrator (or any user with sufficient privileges), can change critical account settings such as email and username. The attack requires social engineering to trick the administrator into clicking a specially crafted link or performing an action that submits the forged request. The vulnerability does not allow direct compromise without user interaction and does not impact confidentiality or availability directly but can affect the integrity of user account data. The CVSS 3.1 base score is 4.3 (medium severity), reflecting that the attack vector is network-based, requires no privileges, but does require user interaction, and impacts integrity only. No known exploits are currently in the wild, and no patches have been published yet. The vulnerability is classified under CWE-352, which covers CSRF weaknesses. Given that WordPress is widely used across many organizations, especially for public-facing websites, this vulnerability could be leveraged to manipulate administrator accounts, potentially leading to further compromise if combined with other vulnerabilities or weak security practices.

For European organizations, the impact of this vulnerability primarily concerns the integrity of administrative user accounts on WordPress sites using the affected plugin. Unauthorized changes to email and username settings could disrupt account management, potentially locking out legitimate administrators or enabling attackers to conduct further social engineering or phishing attacks. While the vulnerability itself does not directly expose sensitive data or cause service outages, it can be a stepping stone for more severe attacks if attackers gain persistent access or escalate privileges. Organizations relying on WordPress for critical web services, customer portals, or internal tools could face operational disruptions or reputational damage if attackers exploit this flaw. The requirement for user interaction (administrator clicking a malicious link) means that effective user awareness and security training can reduce risk. However, given the popularity of WordPress in Europe and the frequent targeting of European organizations by cyber adversaries, this vulnerability should be addressed promptly to prevent exploitation.

1. Immediate mitigation involves disabling or removing the Custom Login And Signup Widget plugin until a secure patched version is released. 2. If removal is not feasible, restrict administrative access to trusted networks or IP addresses to reduce exposure. 3. Implement Web Application Firewall (WAF) rules that detect and block suspicious POST requests to /frndzk_adminclsw.php or requests lacking valid nonce tokens. 4. Educate administrators about the risks of clicking unsolicited links and encourage the use of multi-factor authentication (MFA) to reduce the impact of compromised credentials. 5. Monitor administrative account changes and set up alerts for unusual modifications to email or username settings. 6. Regularly update WordPress core and plugins to the latest versions and subscribe to security advisories from plugin vendors and WordPress security teams. 7. Once a patch is available, apply it immediately and verify nonce validation is correctly implemented. 8. Conduct security audits and penetration testing focusing on CSRF and other web vulnerabilities to identify and remediate similar issues proactively.