cvedb.io
CVE-2026-27586
CRITICAL · CVSS 9.1
EPSS exploitation probability: 0%
Published 2026-02-24T17:29:03.793 · Last modified 2026-06-17T10:27:20.880

Summary

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

Affected products

caddyserver — caddy

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.