CVE-2026-34790 Overview
CVE-2026-34790 is a directory traversal vulnerability affecting Endian Firewall version 3.3.25 and prior. The vulnerability allows authenticated users to delete arbitrary files on the system by exploiting improper input validation in the remove ARCHIVE parameter of the /cgi-bin/backup.cgi endpoint. The parameter value is used to construct a file path without proper sanitization of directory traversal sequences (e.g., ../), which is then passed directly to an unlink() system call.
Critical Impact
Authenticated attackers can delete critical system files, potentially causing denial of service, disrupting firewall operations, or creating conditions for further exploitation.
Affected Products
- Endian Firewall version 3.3.25
- Endian Firewall versions prior to 3.3.25
Discovery Timeline
- 2026-04-02 - CVE-2026-34790 published to NVD
- 2026-04-02 - Last updated in NVD database
Technical Details for CVE-2026-34790
Vulnerability Analysis
This directory traversal vulnerability (CWE-22) resides in the backup management functionality of Endian Firewall's web interface. The /cgi-bin/backup.cgi script accepts a remove ARCHIVE parameter intended to allow authenticated users to delete backup files. However, the application fails to properly validate or sanitize this input before using it in file system operations.
The vulnerability requires network access and a low-privilege authenticated session to exploit. While confidentiality is not directly impacted, successful exploitation can lead to high integrity impact through unauthorized file deletion and low availability impact due to potential service disruption.
Root Cause
The root cause is improper input validation (CWE-22: Improper Limitation of a Pathname to a Restricted Directory). The remove ARCHIVE parameter value is concatenated into a file path without filtering or validating directory traversal sequences such as ../. This unsanitized path is then passed to the unlink() function, which deletes the file at the specified location regardless of whether it resides within the intended backup directory.
Attack Vector
The attack is network-based and requires authentication. An attacker with valid credentials can craft a malicious HTTP request to the /cgi-bin/backup.cgi endpoint, supplying a remove ARCHIVE parameter containing directory traversal sequences. For example, submitting a value like ../../../etc/passwd would cause the application to attempt deletion of the /etc/passwd file. The attacker can systematically target critical system files, configuration files, or log files to disrupt firewall operations or cover their tracks.
The vulnerability mechanism involves the CGI script accepting user input for the archive filename, constructing a file path by appending this input to a base directory path, and passing the resulting path to unlink() without validation. Technical details are available in the VulnCheck Advisory.
Detection Methods for CVE-2026-34790
Indicators of Compromise
- HTTP requests to /cgi-bin/backup.cgi containing ../ sequences in the remove ARCHIVE parameter
- Unusual file deletion events in system logs, particularly for files outside the backup directory
- Missing critical system configuration files with no administrative explanation
- Web server access logs showing repeated requests to the backup.cgi endpoint with suspicious parameter values
Detection Strategies
- Implement web application firewall (WAF) rules to detect and block directory traversal patterns in HTTP parameters targeting /cgi-bin/backup.cgi
- Configure intrusion detection systems (IDS) to alert on HTTP requests containing path traversal sequences to firewall management interfaces
- Enable and monitor file integrity monitoring (FIM) for critical system files and directories
- Review web server access logs for anomalous patterns involving the backup management endpoint
Monitoring Recommendations
- Enable verbose logging for the Endian Firewall web management interface
- Monitor file system audit logs for unexpected unlink() operations on system-critical paths
- Set up alerts for authentication events followed by suspicious backup.cgi access patterns
- Implement centralized log collection to detect potential exploitation attempts across multiple devices
How to Mitigate CVE-2026-34790
Immediate Actions Required
- Restrict access to the Endian Firewall web management interface to trusted networks and administrators only
- Review access logs for any indicators of exploitation attempts
- Implement network segmentation to limit exposure of firewall management interfaces
- Consider temporarily disabling the backup functionality if not operationally required until a patch is available
Patch Information
No vendor patch information is currently available in the CVE data. Administrators should monitor the Endian Community Help Section for security updates and patch announcements. Contact Endian support for guidance on remediation options.
Workarounds
- Implement strict network access controls (ACLs) to limit which IP addresses can reach the /cgi-bin/backup.cgi endpoint
- Deploy a web application firewall (WAF) with rules to block requests containing directory traversal patterns
- Restrict backup management functionality to specific administrative accounts with enhanced monitoring
- Consider placing the firewall management interface on an isolated management VLAN
# Example: Restrict access to management interface via iptables
# Allow only trusted management network
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
