CVE-2026-27586
Caddy is an extensible server platform that uses TLS by default.
Published Feb 24, 2026 · updated Jun 17, 2026 · caddyserver caddy
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, two swallowed errors in 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 or 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.
Code
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Timeline
Detection, updates, and resolution for this record.
Feb 24, 2026 · NIST NVD
Detected
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, two swallowed errors in 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 bou
Jun 17, 2026 · NIST NVD
Updated
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, two swallowed errors in 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 bou
Affected
- cpe caddyserver/caddyversion unspecified
Sources
- NIST NVDVulnerability recordCVE-2026-27586
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, two swallowed errors in cause mTLS client certificate authentication to silently fail open when a CA certificate file is missing, unreadable, or malformed.
nvd.nist.gov