CVE-2025-11938 identifies a deserialization vulnerability in ChurchCRM, an open-source church management software, affecting all versions up to 5.18.0. The flaw exists in the setup/routes/setup.php file, where manipulation of certain parameters—DB_PASSWORD, ROOT_PATH, and URL—can trigger unsafe deserialization of user-controlled data. Deserialization vulnerabilities occur when untrusted input is deserialized without proper validation, potentially allowing attackers to execute arbitrary code, escalate privileges, or cause denial of service. This vulnerability can be exploited remotely without requiring authentication or user interaction, but the attack complexity is rated high, indicating that exploitation requires significant skill or specific conditions. The CVSS 4.0 score is 6.3 (medium severity), reflecting limited confidentiality, integrity, and availability impacts with difficult exploitability. Although the exploit has been publicly disclosed, no confirmed active exploitation in the wild has been reported. The vendor was notified early but has not issued a patch or response, increasing the urgency for organizations to implement mitigations. The vulnerability affects a wide range of ChurchCRM versions, which are used primarily by religious organizations for managing member data, events, and communications. Successful exploitation could lead to unauthorized access to sensitive data, manipulation of church records, or disruption of services.

For European organizations, particularly churches and religious institutions using ChurchCRM, this vulnerability poses a risk to the confidentiality and integrity of sensitive member and organizational data. Exploitation could allow attackers to execute arbitrary code on the server, potentially leading to data breaches, unauthorized data modification, or service outages. Given that ChurchCRM often contains personal information of congregants, including contact details and possibly financial data, a breach could have privacy and regulatory implications under GDPR. The availability of church management services could also be disrupted, impacting organizational operations and community activities. Although the attack complexity is high and no active exploits are known, the lack of vendor response and patch availability increases the risk exposure. European organizations with limited cybersecurity resources may be particularly vulnerable to targeted attacks leveraging this flaw.

Until an official patch is released, organizations should implement several specific mitigations: 1) Restrict network access to the setup/routes/setup.php endpoint by limiting it to trusted IP addresses or internal networks to prevent remote exploitation. 2) Employ web application firewalls (WAFs) with custom rules to detect and block suspicious deserialization payloads or manipulation of DB_PASSWORD, ROOT_PATH, and URL parameters. 3) Conduct thorough input validation and sanitization on all parameters that influence deserialization processes, ensuring only expected data types and formats are accepted. 4) Monitor logs for unusual access patterns or error messages related to the setup routes. 5) Consider isolating ChurchCRM instances in segmented network zones with minimal privileges to limit potential impact. 6) Plan and test upgrades to newer versions once the vendor releases a patch addressing this vulnerability. 7) Educate administrators about the risks of deserialization vulnerabilities and the importance of timely updates. These targeted actions go beyond generic advice by focusing on the specific vulnerable component and attack vectors.