Home/CVE/Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, two swallowed errors in `Clien
CVE

CVE-2026-27586

Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, two swallowed errors in `Clien

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.

CRITICAL · CVSS 9.1 EPSS 0.00127
Act now
  • Public exploit or PoC is available
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-755Improper Handling of Exceptional Conditions
▤

Affected Products & Versions

1
caddyserver caddy< 2.11.1
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Go github.com/caddyserver/caddy/v2 HIGH fixed in 2.11.1
⚠

Public Exploits & PoCs

2
pocgist.github.com · 9566c79c76c0b64c57f8bd0716f97c48gist.github.com
pocgithub.com · GHSA-hffm-g8v7-wrv7github.com
▣

Scoring & Timeline

9.1
CRITICAL · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD24 Feb 2026 · 05:29 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/caddyserver/caddy/releases/tag/v2.11.1Release Notes
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