CSRF Bypass Leading to Code Execution in Rejetto HFS

Executive Summary

CVE-2026-61502 is a Cross-Site Request Forgery (CSRF) vulnerability in Rejetto HFS versions 3.0.0 through 3.2.0. The software improperly handles state-changing API requests by accepting them via the GET method, which is typically used for safe, non-modifying operations.

Additionally, HFS exempts GET requests from its anti-CSRF header checks, which are designed to prevent unauthorized actions initiated by a malicious actor. This flaw allows a remote attacker to perform administrative actions, such as creating accounts or modifying configurations, without the administrator's explicit consent.

• The attack can be executed by tricking a logged-in administrator into visiting a crafted URL.
• In default installations, the attack can also succeed without any credentials if it originates from the server's own machine.

Successful exploitation could lead to code execution on the affected system.

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Detection Guidance

To detect this vulnerability on your network or system, you can check the version of Rejetto HFS running. The vulnerability affects versions 3.0.0 through 3.2.0. You can verify the version by accessing the HFS web interface or checking the server's response headers.

• Check the HFS version via the web interface: Open a browser and navigate to the HFS server. The version is often displayed on the main page or in the footer.
• Inspect HTTP response headers: Use a tool like curl to send a request to the HFS server and check the 'Server' header for the version. Example command: curl -I http://<HFS_SERVER_IP>:<PORT>
• Look for signs of unauthorized administrative actions: Review logs for unexpected account creations or configuration changes, especially those originating from unusual IP addresses.

If the version is between 3.0.0 and 3.2.0, the system is vulnerable to CVE-2026-61502.

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Impact Analysis

If you are using Rejetto HFS versions 3.0.0 through 3.2.0, this vulnerability could have several serious impacts:

• Unauthorized administrative actions: An attacker could create new accounts, modify server configurations, or perform other privileged operations without your knowledge.
• Code execution: The attacker could potentially execute arbitrary code on your server, leading to full system compromise.
• Data exposure or manipulation: Sensitive files or data hosted on the server could be accessed, modified, or deleted.
• Service disruption: The attacker could disrupt the availability of the HFS service or the entire server.

The attack can be carried out remotely by tricking an administrator into clicking a malicious link, or in some cases, without any user interaction if the attack originates from the server's own machine.

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Compliance Impact

This vulnerability could impact compliance with several common standards and regulations, depending on the context in which Rejetto HFS is used:

• GDPR (General Data Protection Regulation): If the HFS server processes or stores personal data of EU citizens, this vulnerability could lead to unauthorized access or modification of that data. GDPR requires organizations to implement appropriate security measures to protect personal data, and a CSRF vulnerability may be considered a failure to meet these requirements, potentially resulting in fines or other penalties.
• HIPAA (Health Insurance Portability and Accountability Act): If the HFS server is used in a healthcare setting to store or transmit protected health information (PHI), this vulnerability could lead to unauthorized access or disclosure of PHI. HIPAA requires covered entities to implement safeguards to protect PHI, and a CSRF vulnerability may indicate a failure to meet these requirements, potentially leading to fines or other enforcement actions.
• PCI DSS (Payment Card Industry Data Security Standard): If the HFS server is involved in processing, transmitting, or storing payment card data, this vulnerability could lead to unauthorized access or modification of that data. PCI DSS requires organizations to implement strong security controls, and a CSRF vulnerability may indicate a failure to meet these requirements, potentially resulting in fines or the loss of the ability to process payment cards.
• Other industry-specific regulations: Depending on the industry and the type of data processed or stored by the HFS server, this vulnerability could also impact compliance with other regulations, such as SOX (Sarbanes-Oxley Act) for publicly traded companies or FISMA (Federal Information Security Management Act) for U.S. federal agencies.

To maintain compliance, organizations should promptly apply the available patch (version 3.2.1 or later) and review their security controls to ensure they meet the requirements of relevant standards and regulations.

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Mitigation Strategies

To mitigate this vulnerability, follow these immediate steps:

• Upgrade to the latest version: The vulnerability is fixed in Rejetto HFS version 3.2.1 or later. Download and install the update from the official GitHub repository.
• Restrict access to the HFS admin interface: Limit access to the HFS web interface to trusted IP addresses only, using firewall rules or network segmentation.
• Disable unnecessary administrative functions: Temporarily disable features like account creation or configuration changes until the system is updated.
• Monitor for suspicious activity: Review logs for any unauthorized administrative actions or unusual requests, particularly those using the GET method for state-changing operations.
• Educate administrators: Inform administrators about the risks of clicking on untrusted links or visiting suspicious URLs while logged into the HFS interface.

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