Vulnerability · Published Jun 8, 2026 · Assigned by Checkmk
CVE-2026-8833XSS in urls
High 8.5
In plain English
A high-severity cross-site scripting in Checkmk from Checkmk GmbH. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities).
Severity (CVSS 4.0)8.5High
Exploit odds (30 days)0.1%top 96.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Checkmk GmbH | Checkmk | 2.5.0 – before 2.5.0p52.4.0 – before 2.4.0p312.3.0 – before 2.3.0p482.2.0 |
Weakness: CWE-79 · Vector: 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
References
- https://checkmk.com/werk/20002 vendor-advisory