CVE-2026-26190

Comprehensive Technical Analysis of CVE-2026-26190

1. Vulnerability Assessment and Severity Evaluation

CVE ID: CVE-2026-26190 CVSS Score: 9.8

The vulnerability in Milvus, an open-source vector database designed for generative AI applications, is severe. The CVSS score of 9.8 indicates a critical risk due to the potential for unauthenticated access to sensitive operations and data manipulation. The exposure of TCP port 9091 by default, combined with weak authentication mechanisms, significantly increases the risk of exploitation.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

1. Authentication Bypass: The default exposure of TCP port 9091 allows attackers to bypass authentication mechanisms.
2. Weak Authentication Token: The /expr debug endpoint uses a predictable default authentication token derived from etcd.rootPath, which is set to "by-dev" by default. This token can be easily guessed or brute-forced.
3. Unauthenticated Access to REST API: The full REST API (/api/v1/*) is accessible without any authentication on the metrics/management port, enabling unauthorized access to all business operations.

Exploitation Methods:

1. Arbitrary Expression Evaluation: Attackers can exploit the weak authentication token to evaluate arbitrary expressions, potentially leading to remote code execution (RCE).
2. Data Manipulation: Unauthenticated access to the REST API allows attackers to manipulate data, including inserting, updating, or deleting records.
3. Credential Management: Attackers can manage credentials, potentially gaining further access to the system or other connected services.

3. Affected Systems and Software Versions

Affected Versions:

• Milvus versions prior to 2.5.27
• Milvus versions prior to 2.6.10

Affected Systems:

• Any system running the affected versions of Milvus, particularly those with default configurations exposing TCP port 9091.

4. Recommended Mitigation Strategies

1. Upgrade to Patched Versions: Immediately upgrade to Milvus versions 2.5.27 or 2.6.10, which include fixes for this vulnerability.
2. Network Segmentation: Implement network segmentation to limit access to the Milvus database, ensuring that only trusted systems can communicate with it.
3. Firewall Rules: Configure firewall rules to restrict access to TCP port 9091, allowing only necessary and trusted IP addresses.
4. Authentication Enhancements: Implement strong, non-default authentication mechanisms for all endpoints, including the /expr debug endpoint.
5. Monitoring and Logging: Enable comprehensive monitoring and logging to detect and respond to any unauthorized access attempts.

5. Impact on Cybersecurity Landscape

The discovery and exploitation of this vulnerability highlight the importance of secure default configurations and robust authentication mechanisms in open-source software. The potential for unauthenticated access to critical business operations underscores the need for continuous monitoring and timely patching of software. This vulnerability serves as a reminder for organizations to regularly review and update their security practices, particularly for systems handling sensitive data or operations.

6. Technical Details for Security Professionals

Vulnerability Details:

• Exposed Port: TCP port 9091 is exposed by default, allowing unauthenticated access.
• Weak Token: The /expr debug endpoint uses a weak, predictable authentication token derived from etcd.rootPath (default: "by-dev").
• Unauthenticated REST API: The full REST API (/api/v1/*) is accessible without authentication on the metrics/management port.

Mitigation Steps:

1. Patching: Apply the patches provided in Milvus versions 2.5.27 and 2.6.10.
2. Configuration Changes: Modify the default configuration to use strong, unique authentication tokens and disable unnecessary endpoints.
3. Access Control: Implement strict access control policies to limit exposure to the Milvus database.
4. Intrusion Detection: Deploy intrusion detection systems (IDS) to monitor for suspicious activity related to the exposed endpoints.

References:

• Milvus GitHub Commit
• Milvus Release 2.5.27
• Milvus Release 2.6.10
• Milvus Security Advisory

By addressing these vulnerabilities and implementing robust security measures, organizations can significantly reduce the risk of unauthorized access and data manipulation in their Milvus deployments.