CVE-2017-20209 Nagios Fusion < 4.0.1 XSS via Users/Servers Page
An attacker can inject arbitrary scripts into the Users and Servers pages of Nagios Fusion, potentially executing code 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-2017-20209?
CVE-2017-20209 is a medium-severity cross-site scripting vulnerability in Nagios Fusion, published on 30 Oct 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Nagios Fusion versions prior to 4.0.1 are vulnerable to cross-site scripting (XSS) via the Users and Servers pages. Insufficient validation or escaping of user-supplied input may allow an attacker to inject and execute arbitrary script in the context of a victim's browser.
Weakness: CWE-79
Which versions are affected by CVE-2017-20209?
It affects 1 product.
Products include Nagios Fusion.
How do I fix CVE-2017-20209?
No fix has been published for CVE-2017-20209 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-2017-20209 being exploited?
There is no known exploitation of CVE-2017-20209 in the wild and no public exploit code.
Other vulnerabilities in Nagios Fusion
Sources
Also known as GHSA-vcfc-84hr-mgwm.