CVE-2025-6451 is a critical SQL Injection vulnerability identified in version 1.0 of the Simple Online Hotel Reservation System developed by code-projects. The vulnerability resides in the /admin/delete_pending.php script, specifically in the handling of the 'transaction_id' parameter. An attacker can remotely exploit this flaw by manipulating the 'transaction_id' argument without requiring any authentication or user interaction. This manipulation allows the injection of malicious SQL code, potentially enabling unauthorized access to the backend database. The vulnerability affects the confidentiality, integrity, and availability of the system's data, as attackers could extract sensitive information, modify or delete records, or disrupt normal operations. The CVSS 4.0 base score is 6.9 (medium severity), reflecting the network attack vector, low attack complexity, no privileges or user interaction required, and limited scope and impact on confidentiality, integrity, and availability. Although no public exploits are currently known in the wild, the vulnerability has been publicly disclosed, increasing the risk of exploitation. No official patch links are provided, but applying vendor patches or mitigations is recommended once available. The vulnerability's presence in an administrative function increases the risk, as administrative interfaces often have elevated privileges and access to sensitive data. The lack of authentication requirement and remote exploitability make this vulnerability particularly dangerous in exposed deployments of the affected software.

For European organizations using the Simple Online Hotel Reservation System version 1.0, this vulnerability poses a significant risk. Exploitation could lead to unauthorized access to customer data, including personal and payment information, violating data protection regulations such as the GDPR. This could result in financial losses, reputational damage, and regulatory penalties. The ability to delete or alter pending transactions could disrupt booking operations, causing service outages and customer dissatisfaction. Given the hospitality sector's importance in Europe, especially in countries with large tourism industries, the impact could be widespread. Additionally, attackers could leverage this vulnerability as a foothold for further network compromise, potentially affecting broader IT infrastructure. The remote and unauthenticated nature of the exploit increases the likelihood of attacks, especially if the system is internet-facing without adequate network protections.

1. Immediate application of any available patches or updates from the vendor is critical. If no patch is available, implement input validation and parameterized queries or prepared statements to prevent SQL injection in the affected script (/admin/delete_pending.php). 2. Restrict access to the administrative interface by IP whitelisting or VPN-only access to reduce exposure. 3. Employ Web Application Firewalls (WAFs) with rules specifically targeting SQL injection patterns, particularly on the 'transaction_id' parameter. 4. Conduct thorough code reviews and security testing on all input handling in the application to identify and remediate similar vulnerabilities. 5. Monitor logs for suspicious activity related to SQL injection attempts and anomalous database queries. 6. Segregate the database with least privilege principles, ensuring the web application account has minimal permissions to limit the impact of a successful injection. 7. Educate IT and security teams about this vulnerability and ensure incident response plans include steps for SQL injection attacks. 8. Consider migrating to a more secure or actively maintained hotel reservation system if patching or mitigation is not feasible.