CVE-2026-39422 MaxKB has Stored XSS via ChatHeadersMiddleware

Medium 6.9 Published 14 Apr 2026 Updated 14 Apr 2026

Attackers can inject malicious scripts via application name or icon fields, leading to arbitrary JavaScript execution in victims' browsers.

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

What is CVE-2026-39422?

CVE-2026-39422 is a medium-severity cross-site scripting vulnerability in 1Panel-dev MaxKB, published on 14 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain a Stored Cross-Site Scripting (XSS) vulnerability through the application name or icon fields when creating an application. When a victim visits the public chat interface (/ui/chat/{access_token}), the ChatHeadersMiddleware retrieves the application data and directly inserts the unescaped application name and icon into the HTML response via string replacement. This allows an attacker to execute arbitrary JavaScript in the victim's browser context. This issue has been fixed in version 2.8.0.

Weakness: CWE-79

Which versions are affected by CVE-2026-39422?

It affects 1 product.

Products include Maxkb Maxkb.

How do I fix CVE-2026-39422?

No fix has been published for CVE-2026-39422 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-2026-39422 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39422 exists.

Sources

Also known as GHSA-wf7p-3jq5-q52w.