What is CVE-2017-9781?

CVE-2017-9781 is a medium-severity vulnerability in Check Mk Project, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2017-06-21.

How severe is CVE-2017-9781?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Check Mk Project

CVE-2017-9781

A cross site scripting (XSS) vulnerability exists in Check_MK versions 1.4.0x prior to 1.4.0p6, allowing an unauthenticated remote attacker to inject arbitrary HTML or JavaScript via the _username parameter when attempting authentication to webapi.py, which is returned unencoded with content type text/html.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2017-06-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.016 (74.2th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 74th percentile — 74.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.016 · newest: 0.016 · change: 0.000

Affected products

Check Mk Project — versions 1.4.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

git.mathias-kettner.de/git/
www.tenable.com/security/research/tra-2017-21 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2017-9781?: CVE-2017-9781 is a medium-severity vulnerability in Check Mk Project, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2017-06-21.
How severe is CVE-2017-9781?: Medium severity. CVSS v3 base score is 6.1 out of 10.