CVE-2025-66099 identifies a missing authorization vulnerability in the ThemeAtelier Chat Help product, affecting versions up to and including 3.1.3. The vulnerability arises from incorrectly configured access control security levels, which fail to properly restrict user permissions within the chat help system. This misconfiguration allows an attacker to bypass authorization checks, potentially gaining unauthorized access to chat functionalities or sensitive data managed by the application. The flaw does not require prior authentication or user interaction, increasing its exploitation risk. Although no exploits have been reported in the wild, the vulnerability's presence in a customer support chat tool could lead to unauthorized data disclosure, manipulation of chat sessions, or disruption of support services. The absence of a CVSS score necessitates an assessment based on the impact on confidentiality, integrity, and availability, the ease of exploitation, and the scope of affected systems. The vulnerability impacts confidentiality and integrity primarily, as unauthorized users may access or alter chat data. The product is used in various organizational environments, especially those relying on integrated chat support solutions. The lack of vendor patches at the time of disclosure highlights the need for immediate mitigation through configuration reviews and monitoring.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of customer support communications and data. Unauthorized access to chat help systems can lead to exposure of sensitive customer information, manipulation of support interactions, and potential reputational damage. Organizations in sectors with high customer interaction, such as finance, telecommunications, and e-commerce, may face increased risks. The disruption or compromise of chat help services could also impact operational availability, affecting customer satisfaction and trust. Given the vulnerability does not require authentication or user interaction, attackers can exploit it remotely with relative ease if the system is exposed. This elevates the threat level for organizations that have deployed Chat Help in externally accessible environments without additional protective controls. Furthermore, the lack of known exploits currently provides a window for proactive defense but also means organizations must act swiftly to prevent future exploitation.

Organizations should immediately audit their Chat Help deployments to identify affected versions (up to 3.1.3) and restrict external access to the chat help interface through network segmentation or firewall rules. Until an official patch is released by ThemeAtelier, administrators should review and tighten access control configurations to ensure that only authorized users can access sensitive chat functionalities. Implementing strong authentication and authorization mechanisms around the chat help system can reduce exploitation risk. Monitoring and logging access to the chat help interface should be enhanced to detect anomalous or unauthorized activities promptly. Additionally, organizations should consider deploying web application firewalls (WAFs) with custom rules to block unauthorized requests targeting the chat help endpoints. Regularly checking for vendor updates and applying patches as soon as they become available is critical. Finally, educating support staff about potential social engineering attempts that might leverage this vulnerability can help mitigate indirect exploitation.