---
cve: "CVE-2026-27586"
severity: "HIGH"
cvss: 8.8
epss: "27%"
vendor: "caddyserver"
kev: false
exploited: false
published: "2026-02-24 17:29:03"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-18T13:28:36+02:00"
---

# CVE-2026-27586

> 8.8 HIGH · 🧪 PoC

## Beschreibung

Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, two swallowed errors in `ClientAuthentication.provision()` cause mTLS client certificate authentication to silently fail open when a CA certificate file is missing, unreadable, or malformed. The server starts without error but accepts any client certificate signed by any system-trusted CA, completely bypassing the intended private CA trust boundary. Any deployment using `trusted_ca_cert_file` or `trusted_ca_certs_pem_files` for mTLS will silently degrade to accepting any system-trusted client certificate if the CA file becomes unavailable. This can happen due to a typo in the path, file rotation, corruption, or permission changes. The server gives no indication that mTLS is misconfigured. Version 2.11.1 fixes the vulnerability.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 6610e2f1bd8f54853006eefd3849c9965190e57f (Commit)

## Referenzen

- <https://github.com/caddyserver/caddy/security/advisories/GHSA-hffm-g8v7-wrv7>
- <https://gist.github.com/moscowchill/9566c79c76c0b64c57f8bd0716f97c48>
- <https://github.com/caddyserver/caddy/releases/tag/v2.11.1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-27586) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_