CVE-2026-0674 identifies a missing authorization vulnerability in the Campaign Monitor for WordPress plugin, specifically affecting the forms-for-campaign-monitor component in versions up to and including 2.9.0. The vulnerability arises due to incorrectly configured access control security levels, which fail to properly restrict unauthorized users from accessing or manipulating form-related functionalities. This can allow attackers to bypass intended authorization checks, potentially enabling unauthorized data submission, modification, or retrieval through the plugin’s integration with Campaign Monitor services. Since the plugin is widely used to manage email marketing campaigns via WordPress, exploitation could lead to unauthorized access to campaign data or manipulation of subscriber lists. The vulnerability does not require prior authentication or user interaction, increasing its risk profile. No CVSS score has been assigned yet, and no known exploits have been reported in the wild, but the potential for abuse remains significant. The issue was published in early 2026, and no official patches or updates have been linked yet, emphasizing the need for vigilance and interim mitigations. The root cause is a failure in enforcing proper authorization checks within the plugin’s codebase, which is a common security oversight in web applications integrating third-party services.

For European organizations, the impact of CVE-2026-0674 could be substantial, especially for those relying on WordPress sites integrated with Campaign Monitor for managing marketing campaigns and subscriber data. Unauthorized access could lead to exposure or alteration of sensitive customer information, undermining data confidentiality and integrity. This may result in reputational damage, regulatory non-compliance (notably with GDPR), and potential financial losses due to phishing or fraud stemming from manipulated campaign content. Additionally, attackers could disrupt marketing operations by injecting malicious content or disabling campaign functionalities, impacting availability. The ease of exploitation without authentication increases the threat level, making it a critical concern for organizations with public-facing WordPress installations. The lack of known exploits currently provides a window for proactive defense, but the vulnerability’s presence in a widely used plugin means the attack surface is broad across Europe.

Until an official patch is released, European organizations should implement several specific mitigations: 1) Restrict access to WordPress administrative and plugin-related endpoints via IP whitelisting or VPNs to limit exposure. 2) Employ Web Application Firewalls (WAFs) with custom rules to detect and block unauthorized attempts targeting the forms-for-campaign-monitor functionality. 3) Conduct thorough audits of user roles and permissions within WordPress to ensure least privilege principles are enforced. 4) Monitor logs for unusual activity related to Campaign Monitor plugin endpoints, including unexpected POST or GET requests. 5) Temporarily disable or remove the Campaign Monitor plugin if feasible, especially on high-risk or sensitive sites. 6) Educate web administrators about the vulnerability and encourage prompt application of updates once available. 7) Implement network segmentation to isolate marketing systems from critical infrastructure. These targeted actions go beyond generic advice and address the specific nature of the missing authorization flaw.