CVE-2023-53689 — Nagios Fusion versions prior to 4

Nagios Fusion versions prior to 4.2.0 contain a reflected cross-site scripting (XSS) vulnerability in the license key configuration flow that can result in execution of attacker-controlled script in the browser of a user who follows a crafted URL. While the application server its

01What is this vulnerability?

Nagios Fusion versions prior to 4.2.0 contain a reflected cross-site scripting (XSS) vulnerability in the license key configuration flow that can result in execution of attacker-controlled script in the browser of a user who follows a crafted URL. While the application server itself is not directly corrupted by the reflected XSS, the resulting browser compromise can lead to credential/session…

02Affected products

No structured affected-product list available — see references below for vendor advisories.

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2025-10-30T22:15:42.633
• Last modified: 2026-10-18T00:10:00.123

09References

• www.nagios.com — https://www.nagios.com/changelog/nagios-fusion/
• www.nagios.com — https://www.nagios.com/products/security/#fusion
• www.vulncheck.com — https://www.vulncheck.com/advisories/nagios-fusion-license-information-reflected…