CVE-2025-26511 is a vulnerability classified under CWE-863 (Incorrect Authorization) found in the NetApp Instaclustr fork of Stratio's Cassandra-Lucene-Index plugin integrated with Apache Cassandra 4.x. This plugin enhances Cassandra with Lucene-based indexing capabilities. The vulnerability exists in versions 4.0-rc1-1.0.0 through 4.0.16-1.0.0 and 4.1.2-1.0.0 through 4.1.8-1.0.0. It allows an authenticated Cassandra user to bypass the role-based access control (RBAC) mechanism, enabling privilege escalation remotely without requiring user interaction. The CVSS v3.1 score of 8.8 reflects a high-severity rating, with network attack vector, low attack complexity, and privileges required at a low level, but no user interaction needed. Successful exploitation can compromise confidentiality, integrity, and availability of the Cassandra database, potentially allowing unauthorized data access, modification, or disruption of services. Although no active exploits have been reported, the vulnerability's nature makes it a significant risk for environments relying on this plugin for indexing and search capabilities. The lack of available patches at the time of publication necessitates immediate attention to access controls and monitoring to mitigate risk.

For European organizations, the impact of CVE-2025-26511 is substantial, especially for those utilizing Apache Cassandra with the vulnerable Instaclustr fork of the Cassandra-Lucene-Index plugin. Exploitation could lead to unauthorized data access, data manipulation, or denial of service, affecting critical business operations and potentially violating data protection regulations such as GDPR. Industries like finance, telecommunications, healthcare, and government, which often rely on Cassandra for large-scale data storage and real-time analytics, face increased risk of data breaches and operational disruption. The ability to escalate privileges remotely without user interaction increases the threat surface, making insider threats or compromised low-privilege accounts particularly dangerous. The absence of known exploits currently provides a window for proactive defense, but the high CVSS score indicates that once exploited, the consequences could be severe, including loss of customer trust, regulatory penalties, and financial losses.

1. Monitor official NetApp and Instaclustr advisories closely for patches addressing CVE-2025-26511 and apply them immediately upon release. 2. Until patches are available, restrict access to Cassandra clusters running the vulnerable plugin to trusted administrators only, minimizing the number of authenticated users. 3. Implement strict network segmentation and firewall rules to limit access to Cassandra nodes from untrusted networks. 4. Enhance logging and monitoring of Cassandra user activities, focusing on unusual privilege escalations or access patterns. 5. Conduct regular audits of RBAC configurations to ensure no excessive privileges are granted. 6. Consider deploying additional security controls such as database activity monitoring (DAM) solutions to detect and alert on suspicious queries or commands. 7. Educate administrators and developers about the risks of privilege escalation vulnerabilities and enforce the principle of least privilege. 8. Evaluate alternative indexing solutions or plugin versions if immediate patching is not feasible, to reduce exposure.