CVE-2026-27586CRITICAL 9.1EPSS p18.1%

CVE-2026-27586CVE-2026-27586

Description

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.

Scoring

CVSS 3.19.1 (CRITICAL)
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS0.27% probability of exploitation · percentile 18.1% · 2026-06-19T12:03:05Z
Published2026-02-24
Last modified2026-02-25

Underlying weaknesses· 1

CWE-755

References

  1. https://gist.github.com/moscowchill/9566c79c76c0b64c57f8bd0716f97c48
  2. https://github.com/caddyserver/caddy/releases/tag/v2.11.1
  3. https://github.com/caddyserver/caddy/security/advisories/GHSA-hffm-g8v7-wrv7

1

TypeTargetConfidenceTier
WeaknessImproper Handling of Exceptional Conditionscwe-7550%live

Related by meaning· 6

Nearest entities by semantic similarity across the cs-graph corpus.

CVE
CVE-2026-27588
CVE
CVE-2026-27587
CVE
CVE-2026-30851
CVE
CVE-2026-27590
CVE
CVE-2026-29145
CVE
CVE-2026-42011
Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.