What is CVE-2019-20139?

CVE-2019-20139 is a medium-severity vulnerability in Nagios Xi, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2019-12-30.

How severe is CVE-2019-20139?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Is CVE-2019-20139 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

XSS in Nagios Xi

CVE-2019-20139

In Nagios XI 5.6.9, XSS exists via the nocscreenapi.php host, hostgroup, or servicegroup parameter, or the schedulereport.php hour or frequency parameter. Any authenticated user can attack the admin user.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2019-12-30 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.261 (97.9th percentile), scored 2026-09-30.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 98th percentile — 97.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.261 · newest: 0.261 · change: 0.000

Affected products

Nagios Xi — versions 5.6.9

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

Public proof-of-concept exploits

ARPSyndicate/cve-scores

References

code610.blogspot.com/2019/12/multiple-xss-bugs-in-nagios-569.html (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2019-20139?: CVE-2019-20139 is a medium-severity vulnerability in Nagios Xi, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2019-12-30.
How severe is CVE-2019-20139?: Medium severity. CVSS v3 base score is 5.4 out of 10.
Is CVE-2019-20139 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.