CVE-2017-11507: A cross site scripting (XSS) vulnerability exists in Check_MK versions 1.2.8x prior to 1.2.8p25 and 1.4.0x pri

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MEDIUM 6.1DOWNGRADE

CVE-2017-11507 is a medium-severity flaw (CVSS 6.1) affecting check mk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A cross site scripting (XSS) vulnerability exists in Check_MK versions 1.2.8x prior to 1.2.8p25 and 1.4.0x prior to 1.4.0p9, allowing an unauthenticated attacker to inject arbitrary HTML or JavaScript via the output_format parameter, and the username parameter of failed HTTP basic authentication attempts, which is returned unencoded in an internal server error page.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.0% (top 36%)
CISA exploited list	No
Weakness	CWE-79
Published	2017-12-11
Last modified	2026-06-17

Publisher (CNA): Tenable Network Security, Inc. · Vendor: check mk project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2017-12-11 16:29 UTCPublished CVE record published
2026-06-17 01:01 UTCUpdated Record last modified

check mk project check mk DOWNGRADE

Affected: 1.2.8 · 1.2.8 b1 · 1.2.8 b10 · 1.2.8 b11 · 1.2.8 b2 · 1.2.8 b3 · 1.2.8 b4 · 1.2.8 b5

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.2.8

1. Check installed version

apt-cache policy check-mk || rpm -q check-mk || check-mk --version

2. No fixed release: DOWNGRADE to a release before 1.2.8 (Debian / Ubuntu)

apt-cache madison check-mk sudo apt install check-mk=<VERSION_BEFORE_1.2.8> sudo apt-mark hold check-mk

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list check-mk sudo dnf downgrade check-mk-<VERSION_BEFORE_1.2.8> sudo dnf versionlock add check-mk

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2017-11507?

check mk: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-11507 being exploited?

CVE-2017-11507 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2017-11507 affect?

CVE-2017-11507 affects check mk. Severity is medium (CVSS 6.1). A cross site scripting (XSS) vulnerability exists in Check_MK versions 1.2.8x prior to 1.2.8p25 and 1.4.0x prior to 1.4.0p9, allowing an unauthenticated attacker to inject arbitrary HTML or JavaScript via the output_format parameter, and th

How urgent is CVE-2017-11507?

Priority 42/100. Public exploit reference

Related CVEs

CVE-2017-9781 MEDIUM 6.1 DOWNGRADE A cross site scripting (XSS) vulnerability exists in Check_MK versions 1.4.0x prior to 1.4.0p6, allowing an un
CVE-2014-0243 MEDIUM 5.5 UPGRADE Check_MK through 1.2.5i2p1 allows local users to read arbitrary files via a symlink attack to a file in /var/l

References

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