CVE-2025-26467 is a high-severity privilege escalation vulnerability affecting Apache Cassandra, specifically version 4.0.16. The vulnerability arises from a CWE-267 issue, where privileges are defined with unsafe actions. In this case, a user granted MODIFY permission on all keyspaces within a Cassandra cluster can exploit unsafe actions on system resources to escalate their privileges to that of a superuser. This escalation allows the attacker to gain full administrative control over the Cassandra cluster, potentially compromising confidentiality, integrity, and availability of the data stored. The vulnerability is notable because it affects a critical permission level (MODIFY on all keyspaces) that might be granted to operational users or applications, and the exploit does not require user interaction. The advisory highlights that the fix for a related vulnerability (CVE-2025-23015) was incorrectly applied in version 4.0.16, leaving it vulnerable. Users are recommended to upgrade to version 4.0.17 where the issue is resolved. Other affected series (3.0, 3.11, 4.1, 5.0) should follow guidance from CVE-2025-23015. Although no known exploits are currently reported in the wild, the vulnerability’s high CVSS score (8.8) and the nature of privilege escalation make it a critical risk for organizations relying on Apache Cassandra for data storage and management.

For European organizations, the impact of CVE-2025-26467 can be severe. Apache Cassandra is widely used in industries requiring scalable and highly available databases, including finance, telecommunications, healthcare, and government sectors. A successful privilege escalation attack could lead to unauthorized data access, data manipulation, or deletion, severely impacting data confidentiality and integrity. This could result in regulatory non-compliance, especially under GDPR, leading to heavy fines and reputational damage. Additionally, availability could be compromised if attackers disrupt cluster operations or delete critical data. Given the potential for superuser access, attackers could also create persistent backdoors or manipulate audit logs, complicating incident response. The vulnerability’s exploitation could affect multi-tenant environments or cloud deployments common in Europe, increasing the risk of cross-customer data breaches. The absence of required user interaction and the network attack vector (AV:N) further increase the risk of automated or remote exploitation.

European organizations should take immediate and specific actions beyond generic patching advice: 1) Upgrade all Apache Cassandra 4.0 series deployments from 4.0.16 to 4.0.17 or later to apply the correct fix. For other versions (3.0, 3.11, 4.1, 5.0), follow the remediation steps outlined in CVE-2025-23015 advisories. 2) Review and audit all users and roles granted MODIFY permission on all keyspaces. Limit this permission strictly to trusted administrators and avoid broad assignments. 3) Implement strict role-based access control (RBAC) policies and segregate duties to minimize privilege exposure. 4) Monitor Cassandra audit logs for unusual privilege escalations or administrative actions, and enhance logging to detect exploitation attempts. 5) Employ network segmentation and firewall rules to restrict access to Cassandra clusters only to authorized hosts and users. 6) Conduct penetration testing and vulnerability assessments focusing on privilege escalation paths within Cassandra environments. 7) Prepare incident response plans specifically addressing potential exploitation of this vulnerability, including rapid isolation and forensic analysis capabilities.