The vulnerability identified as CVE-2025-64227 affects the BoldGrid Client Invoicing plugin by Sprout Invoices, specifically versions up to and including 20.8.7. It is a deserialization of untrusted data vulnerability, which means the plugin improperly processes serialized data from untrusted sources. This flaw enables object injection attacks, where an attacker can craft malicious serialized objects that, when deserialized by the plugin, can alter program flow or execute arbitrary code. Deserialization vulnerabilities are particularly dangerous because they can lead to remote code execution, privilege escalation, or data manipulation without requiring authentication or user interaction. The plugin is commonly used within WordPress environments to manage client invoicing, making it a target for attackers aiming to disrupt financial operations or steal sensitive client data. Although no public exploits are currently known, the nature of the vulnerability suggests that exploitation could be straightforward for skilled attackers. The absence of a CVSS score indicates that the vulnerability is newly published and pending detailed scoring. The issue stems from insecure coding practices where input data is not properly validated or sanitized before deserialization, violating secure software development principles. This vulnerability demands urgent attention from administrators using the affected plugin to prevent potential compromise.

For European organizations, the impact of CVE-2025-64227 can be significant, especially for small and medium enterprises relying on WordPress and the BoldGrid Client Invoicing plugin for financial operations. Successful exploitation could lead to unauthorized remote code execution, allowing attackers to access sensitive financial data, manipulate invoices, or disrupt billing processes. This compromises confidentiality and integrity of client and business data, potentially leading to financial losses, reputational damage, and regulatory non-compliance under GDPR. Availability could also be affected if attackers deploy ransomware or disrupt invoicing services. Given the plugin’s role in invoicing, attacks could directly impact business continuity and customer trust. The lack of authentication requirements for exploitation increases the threat level, making it easier for attackers to target exposed installations. European organizations with limited cybersecurity resources may be particularly vulnerable if they do not promptly apply mitigations or monitor for suspicious activity.

1. Monitor official BoldGrid and Sprout Invoices channels for security patches addressing this vulnerability and apply updates immediately upon release. 2. Until patches are available, consider disabling or uninstalling the Client Invoicing plugin if it is not critical to operations. 3. Implement strict input validation and sanitization controls at the web application firewall (WAF) level to detect and block malicious serialized payloads. 4. Restrict access to the WordPress admin and plugin interfaces using IP whitelisting or VPNs to reduce exposure. 5. Conduct regular security audits and code reviews of custom plugins or integrations to identify unsafe deserialization practices. 6. Enable detailed logging and monitoring for unusual activity related to invoicing functions, including unexpected object deserialization attempts. 7. Educate IT and security teams about the risks of deserialization vulnerabilities and encourage rapid incident response readiness. 8. Employ application-layer security tools that can detect and prevent object injection attacks. 9. Backup invoicing data regularly and verify backup integrity to enable recovery in case of compromise.