CVE-2026-21967 is a critical vulnerability identified in Oracle Hospitality OPERA 5, a widely deployed property management system used in the hospitality industry. The flaw exists in the Opera Servlet component and affects multiple supported versions (5.6.19.23, 5.6.25.17, 5.6.26.10, and 5.6.27.4). The vulnerability allows an unauthenticated attacker with network access over HTTP to exploit the system without any user interaction or prior authentication. Exploitation can lead to unauthorized access to sensitive and critical data managed by OPERA 5, including the ability to read, update, insert, or delete certain data elements. Additionally, the attacker can induce a partial denial of service, impacting system availability. The CVSS 3.1 base score of 8.6 reflects high impact on confidentiality, moderate impact on integrity, and moderate impact on availability. The attack vector is network-based with low complexity and no privileges required, making it easily exploitable. Although no exploits have been reported in the wild yet, the vulnerability poses a significant risk due to the critical nature of the data handled by OPERA 5 and its extensive use in hospitality environments globally. The lack of authentication and user interaction requirements increases the attack surface, especially in environments where OPERA 5 is exposed to untrusted networks or the internet. The vulnerability underscores the need for immediate remediation and enhanced network security controls around OPERA 5 deployments.

For European organizations, especially those in the hospitality sector, this vulnerability presents a severe risk. Successful exploitation can lead to unauthorized disclosure of guest and operational data, potentially violating GDPR and other data protection regulations. The ability to modify or delete data could disrupt hotel operations, bookings, billing, and customer service, resulting in financial losses and reputational damage. Partial denial of service could degrade system performance or availability, impacting guest experience and operational continuity. Given the hospitality industry's critical role in Europe's economy and tourism, widespread exploitation could have cascading effects on service providers, partners, and customers. The exposure of sensitive personal data could trigger regulatory fines and legal consequences. Organizations relying on Oracle Hospitality OPERA 5 must consider the risk of targeted attacks by cybercriminals seeking financial gain or espionage, especially in countries with high tourism volumes and international visitors.

1. Apply Oracle's security patches or updates for OPERA 5 as soon as they become available to remediate the vulnerability. 2. Restrict network access to OPERA 5 HTTP interfaces by implementing strict firewall rules and network segmentation, limiting exposure to trusted internal networks only. 3. Employ web application firewalls (WAFs) to detect and block suspicious HTTP requests targeting OPERA 5. 4. Monitor network traffic and system logs for unusual access patterns or unauthorized data modifications related to OPERA 5. 5. Conduct regular security assessments and penetration testing focused on OPERA 5 deployments to identify and address potential weaknesses. 6. Implement strong access controls and multi-factor authentication for administrative interfaces to reduce risk from lateral movement post-exploitation. 7. Educate IT and security teams about this vulnerability and ensure incident response plans include scenarios involving OPERA 5 compromise. 8. Consider isolating OPERA 5 systems from the internet and untrusted networks wherever possible to reduce attack surface. 9. Backup critical OPERA 5 data regularly and verify restoration procedures to mitigate impact from potential data tampering or denial of service.