CVE-2026-27314: Apache Cassandra Privilege Escalation Flaw

CVE-2026-27314 Overview

A privilege escalation vulnerability exists in Apache Cassandra 5.0 when deployed in an mTLS environment using MutualTlsAuthenticator. The flaw allows a user with only CREATE permission to associate their own certificate identity with an arbitrary role, including superuser roles, and subsequently authenticate as that role via the ADD IDENTITY command. This represents a critical authorization bypass that could allow low-privileged users to gain complete administrative control over Cassandra database clusters.

Critical Impact

Attackers with minimal CREATE permissions can escalate to superuser privileges, potentially compromising entire Cassandra database clusters and all stored data.

Affected Products

• Apache Cassandra 5.0 (versions prior to 5.0.7)
• Apache Cassandra deployments using MutualTlsAuthenticator
• mTLS-enabled Cassandra environments

Discovery Timeline

• 2026-04-07 - CVE CVE-2026-27314 published to NVD
• 2026-04-08 - Last updated in NVD database

Technical Details for CVE-2026-27314

Vulnerability Analysis

This vulnerability is classified under CWE-267 (Privilege Defined With Unsafe Actions), indicating a fundamental flaw in how permissions are defined and enforced within Apache Cassandra's mutual TLS authentication mechanism.

The core issue stems from insufficient authorization validation in the ADD IDENTITY command when used in conjunction with the MutualTlsAuthenticator. In a properly secured mTLS environment, certificate identities should be strictly bound to their assigned roles with appropriate permission boundaries. However, the vulnerable implementation allows users possessing only CREATE permissions to bypass these boundaries and associate their certificate identity with any existing role in the system.

The network-based attack vector with low complexity makes this vulnerability particularly concerning for production Cassandra deployments. An authenticated attacker needs only basic CREATE privileges to execute the attack, requiring no user interaction. The successful exploitation results in complete compromise of confidentiality, integrity, and availability of the affected Cassandra cluster.

Root Cause

The root cause lies in improper permission validation within the ADD IDENTITY functionality of the MutualTlsAuthenticator. The authentication subsystem fails to verify whether a user with CREATE permission should be authorized to associate their certificate identity with roles beyond their privilege level. This missing authorization check allows arbitrary role association, effectively bypassing the entire role-based access control mechanism.

Attack Vector

The attack exploits the network-accessible Cassandra service in mTLS-configured environments. An attacker who has obtained legitimate CREATE permissions—which may be granted for routine database operations—can leverage the ADD IDENTITY command to bind their mTLS certificate to a superuser role. Once the identity association is complete, the attacker can authenticate as the superuser, gaining full administrative control over the database cluster.

The attack sequence involves:

1. Authenticating with valid mTLS credentials having CREATE permission
2. Identifying existing superuser or high-privilege roles in the system
3. Using ADD IDENTITY to associate the attacker's certificate with the target role
4. Re-authenticating to assume the elevated privileges of the target role

Detection Methods for CVE-2026-27314

Indicators of Compromise

• Unexpected ADD IDENTITY CQL commands in Cassandra audit logs, particularly those associating certificates with superuser roles
• Anomalous authentication events where users suddenly authenticate as different roles
• Unusual role membership changes or identity associations in the system_auth keyspace
• Sudden privilege escalation patterns in database access logs

Detection Strategies

• Enable and monitor Cassandra audit logging for all ADD IDENTITY operations
• Implement alerting on role association changes, especially those involving superuser or administrative roles
• Deploy database activity monitoring (DAM) solutions to track privilege escalation patterns
• Review system_auth.role_permissions and identity mappings for unauthorized associations

Monitoring Recommendations

• Configure real-time alerts for any modifications to role-identity mappings in mTLS environments
• Establish baseline behavior for normal CREATE permission usage and alert on deviations
• Monitor authentication logs for users authenticating as multiple different roles
• Implement periodic audits of certificate-to-role associations in production clusters

How to Mitigate CVE-2026-27314

Immediate Actions Required

• Upgrade Apache Cassandra to version 5.0.7 or later immediately
• Audit existing role-identity associations in the system_auth keyspace for unauthorized mappings
• Review and restrict CREATE permissions to only trusted users until patching is complete
• Enable comprehensive audit logging to detect any exploitation attempts

Patch Information

Apache has released version 5.0.7 which addresses this privilege escalation vulnerability. Users are strongly recommended to upgrade to this version or later. For detailed patch information, refer to the Apache Mailing List Thread and the OpenWall OSS Security Post.

Workarounds

• Temporarily disable the MutualTlsAuthenticator and switch to an alternative authentication mechanism if possible
• Revoke CREATE permissions from non-essential users until the patch can be applied
• Implement network segmentation to limit access to Cassandra clusters from untrusted networks
• Deploy additional access controls at the network layer to restrict who can connect to Cassandra services

# Review current role-identity associations for suspicious mappings
cqlsh -e "SELECT * FROM system_auth.identity_to_role;"

# Audit users with CREATE permissions
cqlsh -e "SELECT role, resource, permissions FROM system_auth.role_permissions WHERE permissions CONTAINS 'CREATE' ALLOW FILTERING;"