CVE-2023-45859: Hazelcast Auth Bypass Vulnerability

CVE-2023-45859 Overview

CVE-2023-45859 is an authorization bypass vulnerability in Hazelcast, a popular open-source in-memory data grid platform used for distributed computing and caching. The vulnerability exists because some client operations fail to properly check permissions, allowing authenticated users to access data stored in the cluster that they should not have authorization to view or modify.

This improper access control flaw (CWE-922: Insecure Storage of Sensitive Information) enables authenticated attackers with low-privilege access to the Hazelcast cluster to bypass permission checks and potentially read, modify, or corrupt sensitive data distributed across cluster nodes.

Critical Impact

Authenticated users can bypass permission checks to access unauthorized data stored in Hazelcast clusters, potentially leading to data breaches and unauthorized data manipulation in distributed computing environments.

Affected Products

• Hazelcast through version 4.1.10
• Hazelcast 4.2 through 4.2.8
• Hazelcast 5.0 through 5.0.5
• Hazelcast 5.1 through 5.1.7
• Hazelcast 5.2 through 5.2.4
• Hazelcast 5.3 through 5.3.2

Discovery Timeline

• February 28, 2024 - CVE-2023-45859 published to NVD
• May 13, 2025 - Last updated in NVD database

Technical Details for CVE-2023-45859

Vulnerability Analysis

The vulnerability resides in Hazelcast's client operation handling mechanism, where certain operations bypass the security permission framework. In properly secured Hazelcast deployments, client connections should be authenticated and authorized based on configured security policies that restrict access to specific data structures (maps, queues, topics, etc.) within the cluster.

However, due to improper permission validation in affected versions, some client operations execute without verifying whether the authenticated user has the necessary permissions to access the requested data structures. This allows authenticated users with limited permissions to access data they should not be authorized to view or manipulate.

The vulnerability affects distributed data structures and can be exploited over the network by any authenticated client connected to the Hazelcast cluster. The impact includes potential confidentiality breaches through unauthorized data access, as well as integrity and availability impacts if attackers can modify or delete cluster data.

Root Cause

The root cause of CVE-2023-45859 is the failure to implement proper permission checks in certain client operation handlers within the Hazelcast codebase. The security framework does not consistently validate user permissions before executing operations, creating gaps in the authorization layer that authenticated users can exploit to access protected resources.

Attack Vector

The attack vector for this vulnerability is network-based and requires low-privilege authenticated access to the Hazelcast cluster. An attacker must first establish a valid authenticated connection to the cluster using legitimate credentials. Once authenticated, the attacker can craft specific client operations that trigger the vulnerable code paths where permission checks are missing.

The exploitation scenario involves:

1. An attacker obtains valid credentials for a low-privilege Hazelcast cluster user
2. The attacker connects to the cluster using standard Hazelcast client libraries
3. The attacker issues specific operations that bypass permission validation
4. Unauthorized data is retrieved or manipulated without proper authorization checks

Due to the nature of this vulnerability, no specific code example is available. The exploitation relies on standard Hazelcast client operations that inadvertently bypass permission checks. See the GitHub Security Advisory for detailed technical information.

Detection Methods for CVE-2023-45859

Indicators of Compromise

• Unusual data access patterns from authenticated users accessing data structures outside their permission scope
• Audit logs showing client operations on protected resources from users without proper authorization
• Unexpected queries or modifications to sensitive distributed maps or data structures
• Authentication logs showing suspicious activity from service accounts or users with limited privileges

Detection Strategies

• Enable comprehensive audit logging for all Hazelcast client operations to track data access patterns
• Implement monitoring for access control anomalies where users interact with unauthorized data structures
• Deploy security information and event management (SIEM) rules to detect permission bypass attempts
• Monitor Hazelcast cluster logs for unusual client operation patterns from authenticated sessions

Monitoring Recommendations

• Configure Hazelcast management center alerts for unexpected data access patterns
• Implement network monitoring to detect unusual client-to-cluster communication volumes
• Review authentication and authorization logs regularly for signs of privilege abuse
• Establish baseline user behavior metrics to identify anomalous access patterns

How to Mitigate CVE-2023-45859

Immediate Actions Required

• Upgrade Hazelcast to the latest patched version immediately to address the authorization bypass
• Audit existing user permissions and ensure principle of least privilege is applied
• Review recent access logs for potential exploitation attempts
• Temporarily restrict network access to Hazelcast clusters to trusted systems only

Patch Information

Hazelcast has released security patches to address this vulnerability. Organizations should upgrade to patched versions that include proper permission validation for all client operations. The fix is documented in the GitHub Pull Request #25509.

Upgrade to the following minimum versions or later:

• For 4.x: Upgrade beyond 4.1.10 and 4.2.8
• For 5.0.x: Upgrade beyond 5.0.5
• For 5.1.x: Upgrade beyond 5.1.7
• For 5.2.x: Upgrade beyond 5.2.4
• For 5.3.x: Upgrade beyond 5.3.2

Workarounds

• Implement network segmentation to restrict Hazelcast cluster access to trusted networks only
• Enable TLS/SSL encryption for all client-to-cluster communications
• Apply strict firewall rules limiting which hosts can connect to Hazelcast cluster ports
• Implement additional application-layer authorization checks before data operations

# Example: Restrict Hazelcast cluster network access with iptables
# Allow connections only from trusted application servers
iptables -A INPUT -p tcp --dport 5701 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 5701 -j DROP