CVE-2026-4588: Kalcaddle KodBox Info Disclosure Flaw

CVE-2026-4588 Overview

A cryptographic vulnerability has been identified in kalcaddle kodbox version 1.64. The vulnerability exists in the shareSafeGroup function within the file /workspace/source-code/app/controller/explorer/shareOut.class.php, which is part of the Site-level API key Handler component. This flaw involves the use of a hard-coded cryptographic key through manipulation of the sk argument, potentially allowing attackers to bypass cryptographic protections.

Critical Impact

Attackers exploiting this vulnerability could leverage the hard-coded cryptographic key to decrypt sensitive data or forge authenticated requests, compromising the integrity and confidentiality of shared resources within the kodbox file management system.

Affected Products

• kalcaddle kodbox version 1.64
• Site-level API key Handler component
• Share functionality in kodbox explorer module

Discovery Timeline

• 2026-03-23 - CVE CVE-2026-4588 published to NVD
• 2026-03-23 - Last updated in NVD database

Technical Details for CVE-2026-4588

Vulnerability Analysis

This vulnerability falls under CWE-320 (Key Management Errors), specifically relating to the use of hard-coded cryptographic keys. The affected function shareSafeGroup handles share-related security operations and improperly relies on a static cryptographic key embedded within the application code. When cryptographic keys are hard-coded, any attacker who can analyze the application's source code or binary can extract the key and use it to perform unauthorized operations.

The network-accessible nature of this vulnerability means that remote attackers can potentially exploit it, though the attack complexity is considered high due to the specific conditions required for successful exploitation. The exploit has been publicly disclosed, which increases the urgency for affected organizations to address this security issue. The vendor was contacted about this disclosure but did not respond.

Root Cause

The root cause of this vulnerability is the embedding of a static cryptographic key directly within the application source code. The sk argument in the shareSafeGroup function relies on a hard-coded value rather than dynamically generated or securely stored cryptographic material. This design flaw violates fundamental cryptographic best practices, which mandate that keys should be:

• Uniquely generated per installation
• Stored securely outside of application code
• Rotatable without code changes
• Protected from source code disclosure

Attack Vector

The attack vector is network-based, targeting the Site-level API key Handler component. An attacker would need to:

1. Obtain knowledge of the hard-coded cryptographic key (through source code analysis or prior disclosure)
2. Craft requests to the affected endpoint that leverage the sk parameter
3. Bypass share protection mechanisms by utilizing the known key value

The vulnerability allows for potential confidentiality impact, as protected share resources could be accessed without proper authorization. The complexity of the attack is rated as high, and exploitability is considered difficult due to the specific knowledge and conditions required.

Since no verified code examples are available for this vulnerability, the technical mechanism involves the shareSafeGroup function accepting a sk (secret key) parameter that is validated against a hard-coded value rather than a securely generated key. Detailed technical information can be found in the VulnPlus security note.

Detection Methods for CVE-2026-4588

Indicators of Compromise

• Unusual access patterns to share endpoints in kodbox application logs
• Requests to /app/controller/explorer/shareOut.class.php with suspicious sk parameter values
• Unauthorized access to shared resources that should be protected
• Multiple failed authentication attempts followed by successful share access

Detection Strategies

• Monitor application logs for anomalous requests to the shareOut controller
• Implement Web Application Firewall (WAF) rules to detect exploitation attempts targeting the share functionality
• Deploy file integrity monitoring on the affected PHP files to detect unauthorized modifications
• Review access logs for share resources accessed without proper user authentication context

Monitoring Recommendations

• Enable verbose logging for the kodbox share module to capture all requests with sk parameters
• Set up alerts for access to protected shares from unexpected IP addresses or user agents
• Implement rate limiting on share-related API endpoints to slow potential brute-force attempts
• Monitor for source code disclosure attempts that could reveal the hard-coded key

How to Mitigate CVE-2026-4588

Immediate Actions Required

• Audit all shares created with the affected kodbox version for unauthorized access
• Restrict network access to the kodbox application to trusted networks only where possible
• Implement additional authentication layers for sensitive share functionality
• Review application logs for evidence of prior exploitation

Patch Information

As of the last update on 2026-03-23, no official vendor patch has been released for this vulnerability. The vendor was contacted about this disclosure but did not respond. Organizations should monitor the VulDB entry for updates on patch availability and consider alternative mitigations until an official fix is released.

Workarounds

• Replace the hard-coded cryptographic key with a dynamically generated key unique to each installation by modifying the shareOut.class.php file
• Implement additional access controls at the web server or reverse proxy level to restrict access to the share functionality
• Deploy a Web Application Firewall with custom rules to filter requests targeting the vulnerable endpoint
• Consider disabling the share functionality entirely if not business-critical until a patch is available
• Rotate any secrets or keys that may have been protected by the compromised cryptographic implementation

# Configuration example - Restrict access to vulnerable endpoint via nginx
location ~ /app/controller/explorer/shareOut\.class\.php {
    # Allow only trusted internal networks
    allow 10.0.0.0/8;
    allow 192.168.0.0/16;
    deny all;
    
    # Add rate limiting
    limit_req zone=share_limit burst=5 nodelay;
}