CVE-2026-104808 Mitel MiVoice Office 400 stored Cross-Site Scripting

Low 1.9 Published 5 Oct 2026 Updated 5 Oct 2026

An authenticated attacker can inject persistent JavaScript into the Microsoft Exchange mailbox field, causing a denial-of-service condition in the user management portal.

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

What is CVE-2026-104808?

CVE-2026-104808 is a low-severity cross-site scripting vulnerability in Mitel MiVoice Office 400, published on 5 Oct 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

Official description

DigitalCanion has discovered a stored Cross-Site Scripting (XSS) vulnerability that allows an authenticated malicious user to inject persistent JavaScript or HTML content, resulting in a denial-of-service condition within the web application.

The specific flaw exists within the web portal listening on TCP port 443, under Configuration → Users → Users List. The vulnerability occurs in the “Microsoft Exchange mailbox” field, which fails to properly validate or sanitize user-supplied input before storing and rendering it.

By injecting malicious JavaScript into this field, an attacker can cause the payload to execute whenever the affected user properties are accessed. This can prevent access to the affected user properties and result in a denial-of-service condition within the application's user-management functionality.

Weakness: CWE-79

Which versions are affected by CVE-2026-104808?

How do I fix CVE-2026-104808?

No fix has been published for CVE-2026-104808 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-2026-104808 being exploited?

There is no known exploitation of CVE-2026-104808 in the wild and no public exploit code.

Sources

Also known as GHSA-6grq-8xf9-56fp.