CVE-2019-25394 Smoothwall Express 3.1 'modem.cgi' Cross-Site Scripting

Medium 5.3 Published 16 Feb 2026 Updated 5 Mar 2026

Attackers can inject malicious scripts via POST parameters in modem.cgi, leading to arbitrary JavaScript execution in users' browsers.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2019-25394?

CVE-2019-25394 is a medium-severity cross-site scripting vulnerability in Smoothwall Express, published on 16 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

Smoothwall Express 3.1-SP4-polar-x86_64-update9 contains multiple stored cross-site scripting vulnerabilities in the modem.cgi script that allow attackers to inject malicious scripts through POST parameters. Attackers can submit crafted payloads in parameters like INIT, HANGUP, SPEAKER_ON, SPEAKER_OFF, TONE_DIAL, and PULSE_DIAL to execute arbitrary JavaScript in users' browsers when the stored data is retrieved.

Weakness: CWE-79

Which versions are affected by CVE-2019-25394?

It affects 1 product.

Products include Smoothwall Smoothwall Express.

How do I fix CVE-2019-25394?

No fix has been published for CVE-2019-25394 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2019-25394 being exploited?

There is no known exploitation of CVE-2019-25394 in the wild and no public exploit code.

Sources

Also known as GHSA-qcc6-w9r3-h3c3.