CVE-2025-66073 identifies a critical security vulnerability in the WP Webhooks plugin developed by Cozmoslabs, specifically a deserialization of untrusted data issue that leads to object injection. Deserialization vulnerabilities occur when untrusted input is deserialized by an application without proper validation or sanitization, allowing attackers to manipulate serialized objects to execute arbitrary code or alter application behavior. In this case, the WP Webhooks plugin versions up to and including 3.3.8 are affected. WP Webhooks is a popular WordPress plugin that facilitates automation by allowing external systems to trigger actions within WordPress via webhooks. The vulnerability arises because the plugin improperly handles incoming webhook data, deserializing it without sufficient security checks. This flaw enables attackers to craft malicious payloads that, when deserialized, can inject objects leading to remote code execution, privilege escalation, or data manipulation. Exploitation does not require authentication, meaning any attacker can target vulnerable endpoints exposed to the internet. Although no public exploits have been reported yet, the nature of the vulnerability and the widespread use of WordPress and this plugin make it a high-risk issue. The lack of a CVSS score suggests the vulnerability is newly disclosed, with patching or mitigation guidance still pending. The plugin’s role in automating workflows and integrating external systems increases the attack surface and potential impact. Attackers exploiting this vulnerability could compromise website integrity, steal sensitive data, or disrupt services, severely impacting affected organizations.

For European organizations, the impact of CVE-2025-66073 can be substantial. Many businesses and public institutions rely on WordPress for their web presence, often integrating WP Webhooks for automation and third-party service connectivity. Successful exploitation could lead to unauthorized code execution on web servers, resulting in data breaches, defacement, or service outages. Confidential information such as customer data, internal documents, or credentials could be exposed or altered. Integrity of web content and backend processes could be compromised, undermining trust and compliance with data protection regulations like GDPR. Availability may also be affected if attackers deploy ransomware or disrupt services. The risk is heightened for sectors with critical online operations, including e-commerce, government portals, and financial services. Additionally, the ease of exploitation without authentication means attackers can rapidly scan and target vulnerable sites across Europe, amplifying potential damage. The absence of known exploits currently provides a window for proactive defense, but the threat landscape could quickly evolve once exploit code becomes available.

Immediate mitigation steps include monitoring for updates from Cozmoslabs and applying patches as soon as they are released. Until a patch is available, organizations should consider disabling the WP Webhooks plugin or its webhook handling functionality if feasible. Implementing web application firewall (WAF) rules to detect and block suspicious serialized payloads targeting webhook endpoints can reduce exposure. Input validation and sanitization should be enforced at the application or server level to prevent malicious data from being processed. Network segmentation and limiting public access to webhook endpoints can minimize attack surface. Regularly auditing WordPress plugins and removing unused or outdated components reduces risk. Organizations should also monitor logs for unusual activity related to webhook requests and conduct vulnerability scans to identify affected systems. Educating administrators about the risks of deserialization vulnerabilities and ensuring timely patch management are critical. Finally, backing up website data and configurations regularly ensures recovery capability in case of compromise.