CVE-2026-27586
Caddy's mTLS client authentication silently fails open when CA certificate file is missing or malformed
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.
| CWE | CWE-755 |
| Vendor | caddyserver |
| Product | caddy |
| Published | Feb 24, 2026 |
| Last Updated | Feb 26, 2026 |
Get instant alerts for caddyserver caddy
Be the first to know when new unknown vulnerabilities affecting caddyserver caddy are published — delivered to Slack, Telegram or Discord.