CVE-2026-126495 MQTTX through 1.13.3 Stored XSS via Topic Tree and JSON Tree Tooltips
Attackers controlling MQTT topics can inject script that runs in the Electron renderer when users hover tree nodes in MQTTX desktop.
- 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
- Harmful if only installed
- No
- Needs a specific call
- No
- Fix
- None listed
What is CVE-2026-126495?
CVE-2026-126495 is a medium-severity cross-site scripting vulnerability in emqx MQTTX, published on 11 Nov 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
MQTTX desktop through 1.13.3 contains a stored cross-site scripting vulnerability that allows attackers to inject script by publishing malicious MQTT topic names or payloads rendered unescaped in tooltips. Attackers controlling a broker or publishing to subscribed topics can execute script in the Electron renderer, which has nodeIntegration enabled, when victims hover Topic Tree or JSON tree nodes.
Weakness: CWE-79
Which versions are affected by CVE-2026-126495?
An affected version is exposed as installed. No special setting or call is needed.
How do I fix CVE-2026-126495?
No fix has been published for CVE-2026-126495 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-2026-126495 being exploited?
There is no known exploitation of CVE-2026-126495 in the wild and no public exploit code.
Sources
Also known as GHSA-55f4-qr9r-gp5r.