How severe is CVE-2017-20209?

CVE-2017-20209 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2017-20209 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2017-20209?

CVE-2017-20209 affects Nagios Fusion. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2017-20209?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2017-20209 have an EU (EUVD) identifier?

Yes. CVE-2017-20209 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2017-18925.

When was CVE-2017-20209 published?

CVE-2017-20209 was published on 2025-10-30 and last updated on 2026-06-17.

CVE-2017-20209

CVE-2017-20209 is a medium-severity vulnerability in Nagios Fusion with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v4: 5.1
EPSS exploit prediction: 0% (37th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2017-18925
Weakness: CWE-79
Affected product: Nagios Fusion
Published: 2025-10-30
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2017-20209?: 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.
How severe is CVE-2017-20209?: CVE-2017-20209 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2017-20209 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2017-20209?: CVE-2017-20209 affects Nagios Fusion. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2017-20209?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2017-20209 have an EU (EUVD) identifier?: Yes. CVE-2017-20209 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2017-18925.
When was CVE-2017-20209 published?: CVE-2017-20209 was published on 2025-10-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nagios:fusion:4.0.0:*:*:*:*:*:*:*

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