CVE-2026-0674 identifies a missing authorization vulnerability in the Campaign Monitor for WordPress plugin, specifically in the forms-for-campaign-monitor component. This flaw arises from incorrectly configured access control security levels, allowing users with low privileges (PR:L) to perform actions that should be restricted. The vulnerability affects all versions up to and including 2.9.0. Exploitation requires network access (AV:N) but no user interaction (UI:N), and the scope remains unchanged (S:U). The impact is limited to integrity (I:L), meaning attackers can potentially modify campaign-related data or configurations without proper authorization, but confidentiality and availability are not impacted. No known exploits have been reported in the wild, and no patches have been linked yet. The vulnerability was published on January 8, 2026, and assigned a CVSS v3.1 score of 4.3, indicating a medium severity level. The root cause is a failure to enforce proper authorization checks within the plugin's form handling processes, which could allow unauthorized users to manipulate campaign data or settings, potentially undermining marketing efforts or data accuracy.

For European organizations, this vulnerability could lead to unauthorized modifications of marketing campaign data or configurations within WordPress sites using the affected Campaign Monitor plugin. Such unauthorized changes could disrupt marketing operations, cause misinformation in campaign analytics, or damage brand reputation. While the vulnerability does not directly compromise sensitive customer data or site availability, the integrity impact could indirectly affect business processes reliant on accurate campaign data. Organizations heavily dependent on digital marketing and customer engagement platforms integrated with WordPress are at higher risk. The absence of known exploits reduces immediate risk, but the presence of a vulnerability in a widely used plugin necessitates proactive measures. The impact is more pronounced for organizations with multiple users having low-level privileges, as these users could exploit the missing authorization controls.

Organizations should monitor the Campaign Monitor plugin vendor for official patches addressing CVE-2026-0674 and apply them promptly once available. In the interim, administrators should audit and tighten user privilege assignments within WordPress, ensuring that only trusted users have access to campaign management features. Implementing strict role-based access controls (RBAC) and limiting plugin management capabilities to administrators can reduce exploitation risk. Additionally, reviewing and restricting network access to WordPress administrative endpoints can help prevent unauthorized access attempts. Employing web application firewalls (WAFs) with custom rules to detect anomalous requests targeting the forms-for-campaign-monitor component may provide temporary protection. Regularly monitoring logs for suspicious activity related to campaign modifications is also recommended. Finally, organizations should consider isolating marketing plugins in staging environments before deployment to production to detect potential issues early.