CVE-2025-45746: ZKTeco ZKBio CVSecurity Auth Bypass Issue

CVE-2025-45746 Overview

CVE-2025-45746 is a critical authentication bypass vulnerability affecting ZKTeco ZKBio CVSecurity version 6.4.1_R. The vulnerability stems from the use of a hardcoded cryptographic secret within the application, which allows unauthenticated attackers to craft valid JWT (JSON Web Token) tokens and gain unauthorized access to the service console. This represents a fundamental cryptographic flaw classified under CWE-321 (Use of Hard-coded Cryptographic Key) and CWE-798 (Use of Hard-coded Credentials).

Critical Impact

An unauthenticated attacker can forge valid authentication tokens using the hardcoded secret, potentially gaining full access to the service console without any prior credentials or user interaction.

Affected Products

• ZKTeco ZKBio CVSecurity version 6.4.1_R

Discovery Timeline

• 2025-05-13 - CVE-2025-45746 published to NVD
• 2025-05-21 - Last updated in NVD database

Technical Details for CVE-2025-45746

Vulnerability Analysis

This vulnerability exploits a fundamental security weakness in how ZKBio CVSecurity handles JWT-based authentication. The application utilizes a hardcoded secret key for signing and validating JWT tokens, which is a severe cryptographic implementation flaw. When JWT secrets are embedded directly in the application code or configuration, any attacker who discovers or extracts this secret can forge tokens that appear legitimate to the authentication system.

The supplier has disputed the severity of this vulnerability, noting that the service console is typically only accessible from a local area network (LAN) and that service console access does not translate directly to login access or data access within the application software platform. However, in scenarios involving compromised internal networks, malicious insiders, or misconfigured network segmentation, this vulnerability presents a significant risk.

Root Cause

The root cause is the use of a hardcoded cryptographic key (CWE-321) combined with hardcoded credentials (CWE-798) in the JWT implementation. Hardcoding secrets violates the fundamental principle of secure key management, which requires that cryptographic keys be unique per deployment, securely generated, and stored in protected key stores. When secrets are hardcoded, they are consistent across all installations, making them trivial to extract through reverse engineering or source code analysis.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker on the same network segment as the vulnerable ZKBio CVSecurity installation can:

1. Extract or obtain the hardcoded JWT signing secret from the application
2. Craft a malicious JWT token with arbitrary claims (such as administrative privileges)
3. Sign the forged token using the extracted secret
4. Submit the token to the service console to gain unauthorized access

While the supplier notes that the service console is typically LAN-accessible only, this does not eliminate risk from internal threat actors, compromised internal systems, or improperly segmented networks.

Technical details and proof-of-concept information are available in the GitHub PoC Repository.

Detection Methods for CVE-2025-45746

Indicators of Compromise

• Unexpected authentication events to the service console from unusual internal IP addresses
• JWT tokens with suspicious claims or timestamps that don't align with legitimate user sessions
• Service console access logs showing successful authentication without corresponding user login activities
• Multiple authentication attempts from the same source with different user identifiers in rapid succession

Detection Strategies

• Implement monitoring for service console authentication events and correlate with expected user behavior
• Deploy network intrusion detection rules to identify JWT manipulation patterns
• Review application logs for authentication anomalies such as tokens issued outside normal business hours
• Monitor for extraction attempts of configuration files or binaries that may contain the hardcoded secret

Monitoring Recommendations

• Enable detailed logging on the ZKBio CVSecurity service console and forward logs to a SIEM
• Establish baseline metrics for normal service console access patterns to detect deviations
• Configure alerting for any service console access from non-whitelisted IP addresses
• Implement file integrity monitoring on application binaries and configuration files

How to Mitigate CVE-2025-45746

Immediate Actions Required

• Restrict network access to the ZKBio CVSecurity service console using firewall rules and network segmentation
• Implement IP allowlisting to limit service console access to specific administrative workstations
• Review and audit recent service console access logs for signs of unauthorized access
• Consider disabling the service console entirely if it is not operationally required

Patch Information

As of the last NVD update on 2025-05-21, no official vendor patch information has been published. Organizations should monitor ZKTeco's official channels for security updates. The vendor has disputed the severity of this finding, noting the LAN-only access limitation.

Workarounds

• Implement strict network segmentation to ensure the service console is only accessible from a dedicated management VLAN
• Deploy a web application firewall (WAF) or reverse proxy in front of the service console with additional authentication requirements
• Use VPN or jump host architecture to further restrict access to administrative interfaces
• If possible, configure the application to use environment-specific JWT secrets rather than the hardcoded default
• Conduct regular penetration testing of internal network services to identify unauthorized access attempts

# Example: Restrict service console access to specific management IPs using iptables
# Adjust IP ranges and port numbers according to your deployment
iptables -A INPUT -p tcp --dport 8080 -s 192.168.100.10 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -s 192.168.100.11 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP