CVE-2019-25385 in Express
Summary
by MITRE • 02/16/2026
Smoothwall Express 3.1-SP4-polar-x86_64-update9 contains a reflected cross-site scripting vulnerability that allows attackers to inject malicious scripts by manipulating the MACHINE and MACHINECOMMENT parameters. Attackers can send POST requests to the outgoing.cgi endpoint with script payloads to execute arbitrary JavaScript in users' browsers and steal session data.
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Analysis
by VulDB Data Team • 02/18/2026
The vulnerability identified as CVE-2019-25385 resides within Smoothwall Express version 3.1-SP4-polar-x86_64-update9, a network security appliance designed for firewall and routing services. This particular flaw represents a critical cross-site scripting vulnerability that undermines the application's security posture by failing to properly sanitize user input parameters. The vulnerability specifically affects the outgoing.cgi endpoint which processes incoming requests and fails to validate or escape potentially malicious data submitted through HTTP POST requests.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within the web application's handling of the MACHINE and MACHINECOMMENT parameters. When attackers submit malicious payloads through these parameters, the application reflects the unvalidated input back to users' browsers without proper sanitization. This creates an ideal environment for reflected XSS attacks where malicious JavaScript code can be executed in the context of the victim's browser session. The vulnerability operates at the application layer and requires minimal privileges to exploit, making it particularly dangerous in environments where administrators might be logged in with elevated privileges.
The operational impact of this vulnerability extends beyond simple script execution as it enables attackers to hijack user sessions and potentially gain unauthorized access to the Smoothwall management interface. By crafting malicious POST requests to the vulnerable outgoing.cgi endpoint, attackers can inject JavaScript payloads that execute in users' browsers, allowing for session cookie theft, credential harvesting, and potential privilege escalation within the network security appliance. This vulnerability directly violates security principles outlined in the OWASP Top Ten, specifically targeting the "A03:2021-Injection" category and aligning with CWE-79 which describes Cross-site Scripting vulnerabilities. The attack vector is particularly concerning as it can be executed through simple web-based requests without requiring complex exploitation techniques.
Organizations utilizing Smoothwall Express appliances should immediately implement mitigations including input validation and output encoding for all user-supplied parameters, particularly those used in web interface elements. The recommended approach involves implementing strict parameter validation on the server-side for both MACHINE and MACHINECOMMENT parameters, ensuring that all input conforms to expected formats and that potentially dangerous characters are properly escaped or removed. Network segmentation and access controls should be implemented to limit exposure of the vulnerable interface to trusted administrators only, while also considering the implementation of Content Security Policy headers to provide additional defense-in-depth. This vulnerability demonstrates the critical importance of input validation and output encoding practices as outlined in the MITRE ATT&CK framework under the T1203 technique for Exploitation for Credential Access, highlighting how seemingly simple injection flaws can lead to significant security breaches in network infrastructure devices.