CVE-2026-27586

🚨 CRITICAL

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 sil...

Published
Feb 24, 2026
Last Modified
Feb 25, 2026
Views
2
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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.

Affected Products (1)

caddyserver - caddy

Version: *

CVSS Scores

CVSS 3.1 9.1
9.1
CRITICAL
CVSS 2.0 9.1

Additional Information

Source
security-advisories@github.com
State
Analyzed

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