CVE-2025-66055 is a deserialization of untrusted data vulnerability found in the Icegram Email Subscribers & Newsletters WordPress plugin, specifically in versions up to and including 5.9.10. This vulnerability allows for object injection attacks, where an attacker can manipulate serialized data inputs to inject malicious objects during the deserialization process. Deserialization vulnerabilities are critical because they can lead to remote code execution, privilege escalation, or denial of service if exploited successfully. In this case, the vulnerability requires the attacker to have high privileges (PR:H), such as an authenticated administrator or editor role within the WordPress environment, but does not require user interaction (UI:N) and can be exploited remotely over the network (AV:N). The CVSS score of 7.2 reflects the high impact on confidentiality, integrity, and availability, as exploitation could allow attackers to execute arbitrary code, modify or exfiltrate sensitive subscriber data, or disrupt email marketing operations. Although no known exploits are currently reported in the wild, the presence of this vulnerability in a widely used plugin makes it a significant risk. The plugin is commonly used to manage email subscriber lists and newsletters, which are critical for business communications and marketing. The lack of an official patch link suggests that organizations should monitor vendor communications closely for updates. The vulnerability's technical nature requires understanding of PHP object serialization and WordPress plugin architecture, emphasizing the need for secure coding practices and input validation in plugin development.

For European organizations, the impact of CVE-2025-66055 can be substantial, particularly for those relying on Icegram Email Subscribers & Newsletters for managing customer communications and marketing campaigns. Exploitation could lead to unauthorized access to subscriber data, including personal information protected under GDPR, resulting in data breaches and regulatory penalties. Attackers could also execute arbitrary code on the affected web server, potentially compromising the entire WordPress environment and connected systems. This can disrupt business operations, damage reputation, and cause financial losses. Organizations in sectors such as retail, media, and services that heavily depend on email marketing are at higher risk. Additionally, the requirement for high privileges means that insider threats or compromised administrator accounts could be leveraged to exploit this vulnerability. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits after public disclosure. The vulnerability also poses risks to availability, as exploitation could lead to denial of service, affecting communication channels critical for customer engagement.

European organizations should implement the following specific mitigations: 1) Monitor Icegram vendor channels and security advisories closely for the release of an official patch and apply it immediately upon availability. 2) Restrict administrative access to the WordPress environment by enforcing strong authentication mechanisms, including multi-factor authentication, to reduce the risk of privilege abuse. 3) Conduct regular audits of user roles and permissions to ensure only necessary users have high-level access. 4) Implement Web Application Firewalls (WAF) with custom rules to detect and block suspicious serialized data patterns indicative of object injection attempts. 5) Employ runtime application self-protection (RASP) tools to monitor and block malicious deserialization activities. 6) Regularly back up WordPress sites and subscriber data to enable quick recovery in case of compromise. 7) Educate administrators and developers about secure coding practices related to serialization and input validation to prevent similar vulnerabilities in custom plugins or themes. 8) Consider isolating the WordPress environment or running it in a containerized setup to limit the blast radius of a potential exploit. 9) Monitor logs for unusual activity related to plugin usage or deserialization errors. These measures go beyond generic advice by focusing on access control, detection, and environment hardening tailored to this vulnerability's characteristics.