CVE-2025-11975 is a vulnerability classified under CWE-862 (Missing Authorization) affecting the FuseWP WordPress plugin, which synchronizes WordPress user data with email marketing platforms such as Mailchimp, Constant Contact, and ActiveCampaign. The root cause is a missing capability check in the save_changes() function, which is responsible for saving synchronization rules. This omission allows attackers without proper authorization to add or modify sync rules, potentially altering how user data is synchronized or manipulated. The vulnerability affects all versions up to 1.1.23.0. The CVSS 3.1 base score is 4.3 (medium), reflecting that the attack vector is network-based (remote), with low attack complexity, requiring low privileges but no user interaction. The impact is limited to integrity, as confidentiality and availability are not directly affected. No patches or known exploits are currently available, but the vulnerability could be leveraged to disrupt marketing automation workflows or inject malicious sync configurations, potentially leading to data misuse or loss of trust in marketing data accuracy.

The primary impact of this vulnerability is unauthorized modification of synchronization rules between WordPress user data and marketing automation platforms. This could lead to incorrect or maliciously altered user data being sent to email marketing services, resulting in compromised marketing campaigns, data integrity issues, or potential privacy concerns if user data is mishandled. Organizations relying on FuseWP for automated user synchronization may experience disruption in their marketing workflows, loss of data accuracy, or reputational damage if unauthorized changes go undetected. While the vulnerability does not directly expose sensitive data or cause denial of service, the integrity compromise can have downstream effects on business operations and customer trust. Attackers could potentially exploit this to insert malicious rules that exfiltrate data or manipulate user segments for phishing or spam campaigns.

To mitigate this vulnerability, organizations should immediately update the FuseWP plugin to a version that includes proper authorization checks once available. Until a patch is released, administrators should restrict access to the WordPress admin area and specifically limit permissions related to managing FuseWP synchronization rules to trusted users only. Implementing Web Application Firewall (WAF) rules to monitor and block unauthorized attempts to invoke the save_changes() function or related endpoints can provide temporary protection. Regularly audit synchronization rules for unauthorized changes and monitor logs for suspicious activity. Additionally, consider disabling or limiting the FuseWP plugin functionality if it is not critical, or replacing it with alternative plugins that enforce strict authorization controls. Maintaining least privilege principles for WordPress user roles will reduce the risk of exploitation.