CVE-2026-34793: Endian Firewall RCE Vulnerability

CVE-2026-34793 Overview

CVE-2026-34793 is a command injection vulnerability affecting Endian Firewall version 3.3.25 and prior. The vulnerability exists in the /cgi-bin/logs_firewall.cgi script, where authenticated users can execute arbitrary OS commands via the DATE parameter. The parameter value is used to construct a file path that is passed to a Perl open() call, which allows command injection due to incomplete regular expression validation.

Critical Impact

Authenticated attackers can execute arbitrary system commands on the firewall appliance, potentially leading to complete system compromise, data exfiltration, and network pivoting.

Affected Products

• Endian Firewall version 3.3.25
• Endian Firewall versions prior to 3.3.25

Discovery Timeline

• 2026-04-02 - CVE-2026-34793 published to NVD
• 2026-04-02 - Last updated in NVD database

Technical Details for CVE-2026-34793

Vulnerability Analysis

This vulnerability falls under CWE-78 (Improper Neutralization of Special Elements used in an OS Command), commonly known as OS Command Injection. The vulnerability resides in the logs_firewall.cgi script's handling of the DATE parameter.

When processing log file requests, the CGI script constructs a file path using user-supplied input from the DATE parameter. This constructed path is then passed to Perl's open() function. While some input validation exists via regular expression checks, the validation is incomplete and fails to properly sanitize special characters that can be leveraged for command injection in Perl's two-argument open() call.

The network-accessible nature of this vulnerability combined with the low attack complexity makes it particularly dangerous for organizations using Endian Firewall as their perimeter security device. Successful exploitation requires only low-privilege authenticated access, after which an attacker can achieve full compromise of confidentiality, integrity, and availability on the target system.

Root Cause

The root cause of this vulnerability is incomplete input validation on the DATE parameter before it is passed to Perl's open() function. Perl's two-argument open() is known to interpret special characters such as pipe (|) symbols, which can be abused to execute arbitrary shell commands. The regular expression used to validate the DATE parameter fails to account for all potentially dangerous characters, allowing attackers to craft malicious input that bypasses validation and achieves command execution.

Attack Vector

The attack is carried out over the network against the /cgi-bin/logs_firewall.cgi endpoint. An authenticated attacker crafts a malicious DATE parameter value containing shell metacharacters that are not properly filtered by the incomplete regex validation. When the CGI script processes this input and passes it to Perl's open() function, the injected commands are executed with the privileges of the web server process.

The vulnerability exploitation follows this pattern: an attacker with valid credentials sends a crafted HTTP request to the vulnerable endpoint, including specially formatted command injection payloads in the DATE parameter. The inadequate input sanitization allows the payload to reach the Perl open() call, resulting in arbitrary command execution on the underlying operating system. For detailed technical information, refer to the VulnCheck Advisory.

Detection Methods for CVE-2026-34793

Indicators of Compromise

• Unusual HTTP requests to /cgi-bin/logs_firewall.cgi containing special characters such as pipes (|), backticks, or semicolons in the DATE parameter
• Unexpected process spawning from the web server process (httpd or similar)
• Anomalous outbound network connections originating from the firewall appliance
• Suspicious entries in web server access logs showing encoded or obfuscated DATE parameter values

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing shell metacharacters in CGI parameters
• Monitor web server logs for requests to /cgi-bin/logs_firewall.cgi with unusual DATE parameter patterns
• Deploy intrusion detection system (IDS) signatures to identify command injection attempts targeting this specific endpoint
• Conduct regular security audits of firewall appliance logs for unauthorized access attempts

Monitoring Recommendations

• Enable verbose logging on the Endian Firewall appliance to capture all CGI requests
• Configure SIEM alerts for any requests to vulnerable CGI endpoints containing potential injection payloads
• Monitor system process trees for unexpected child processes spawned by web server components
• Implement network traffic analysis to detect command-and-control communications originating from the firewall

How to Mitigate CVE-2026-34793

Immediate Actions Required

• Restrict network access to the Endian Firewall web management interface to trusted IP addresses only
• Review and audit all user accounts with access to the firewall management interface
• Implement additional network-level access controls such as VPN requirements for administrative access
• Monitor for exploitation attempts while awaiting an official patch

Patch Information

At the time of publication, consult the Endian Community Support for the latest security updates and patch availability. Organizations should monitor vendor communications for official patches addressing this command injection vulnerability.

Workarounds

• Implement strict IP-based access control lists (ACLs) limiting access to the web management interface
• Deploy a reverse proxy with input validation rules in front of the Endian Firewall management interface
• Disable the vulnerable CGI script if log viewing functionality is not required in your environment
• Use network segmentation to isolate the firewall management interface from untrusted networks

# Example: Restrict management interface access via iptables
# Add rules to limit access to management port (typically 10443)
iptables -A INPUT -p tcp --dport 10443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 10443 -j DROP