CVE catalog
CVE-2026-8833
Improper neutralization of HTML-encoded characters in the URL validation function in Checkmk <2.5.0p5, <2.4.0p31, <2.3.0p48, and all 2.2.0 versions allows an authenticated user to bypass URL validatio
- Severity
- High · CVSS 8.5
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.14% · Oct 25, 2026
Improper neutralization of HTML-encoded characters in the URL validation function in Checkmk <2.5.0p5, <2.4.0p31, <2.3.0p48, and all 2.2.0 versions allows an authenticated user to bypass URL validation and inject malicious URLs such as javascript: URIs, resulting in cross-site scripting when another user interacts with the crafted link.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Cpe | checkmk | Not reported | Not reported | unknown |
| Cpe | checkmk | Not reported | Not reported | unknown |
| Ubuntu | check-mk | pro | 1.2.6p5-1 | vulnerable |
| Ubuntu | check-mk | pro | 1.2.6p12-1 | vulnerable |
| Ubuntu | check-mk | pro | 1.2.6p12-1ubuntu0.16.04.1 | vulnerable |
| Ubuntu | check-mk | pro | 1.2.6p12-1ubuntu0.16.04.1+esm1 | vulnerable |
| Ubuntu | check-mk | 18.04 | 1.2.8p16-1ubuntu0.1 | vulnerable |
| Ubuntu | check-mk | 18.04 | 1.2.8p16-1ubuntu0.2 | vulnerable |
Fixed-version evidence
OpenFactory catalog packages
No matching packages in this catalog.
Observed:
References
- [https://checkmk.com/werk/20002]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-8833]
- [https://osv.dev/vulnerability/UBUNTU-CVE-2026-8833]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-1817.json]
[CERT-Bund public advisories] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database]