---
id: "CVE-2026-117611"
kind: "vulnerability"
aliases: ["CVE-2026-117611"]
title: "Checkmk: certificate validation trusts a root CA with public keys"
severity: "high"
cvss: 7.1
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["checkmk", "infrastructure", "monitoring", "self-hosted"]
not_affected_if: ["fixed-patch-level"]
published_at: "2026-10-29T10:17:03+00:00"
first_seen_at: "2026-10-29T10:24:25+00:00"
updated_at: "2026-10-29T10:25:21+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117611", "first_seen_at": "2026-10-29T10:24:25+00:00"}]
---

# Checkmk: certificate validation trusts a root CA with public keys

Checkmk's bundled certificate authority stores (from the certifi and webpki-roots packages) include a root CA that trusts eMudhra (emSign) intermediate certificates whose private keys are public. An attacker holding one of those certificates could impersonate a server that Checkmk connects to and be trusted.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Checkmk version against the affected ranges, for example with `omd version` on the Checkmk site.
- Confirm which Checkmk version line the server runs: 2.2.0, 2.3.0, 2.4.0 or 2.5.0 patch levels below the fixed releases are affected.

## Fix

- Checkmk `2.5.0p18` or later
- Checkmk `2.4.0p39` or later
- Checkmk `2.3.0p52` or later
- Checkmk 2.2.0 is end of life; the sources give no fixed version for it.

## Timeline

- 2026-10-29T10:24:25+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117611

## From the sources

Improper certificate validation in Checkmk <2.5.0p18, <2.4.0p39, <2.3.0p52 and 2.2.0 (EOL): the Certificate Authority stores bundled with "certifi" and "webpki-roots" include a root CA that trusts eMudhra (emSign) intermediate certificates whose private keys are public.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_