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 theft and unauthorized administrative actions.
Conclusion & alert: CVE-2023-53689 is rated Low Risk (37.4/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.17%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-05-26 | 0.07% | 0.17% | +0.10% |
| 2 | 2026-03-28 | 0.15% | 0.07% | -0.09% |
| 3 | 2026-01-06 | — | 0.15% | — |
Full EPSS history (4 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 6.0 | 4.0 | MEDIUM |
|
— | — | [email protected] |
| 4.8 | 3.1 | MEDIUM |
|
1.7 | 2.7 | [email protected] |
| URL | Tags |
|---|---|
| https://www.nagios.com/changelog/nagios-fusion/ | Release Notes |
| https://www.nagios.com/products/security/#fusion | Vendor Advisory |
| https://www.vulncheck.com/advisories/nagios-fusion-license-information-reflected-xss | Third Party Advisory |