cve.bz

CVE-2026-27586

8.8 highEPSS 0.3%

High (8.8) in caddyserver caddy. EPSS 0.3% chance of exploitation in the next 30 days. Fixed in github.com/caddyserver/caddy/v2 2.11.1.

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.

Severity

CVSS 4.0

8.8 high
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P

CVSS 3.1

9.1 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS
0.3% chance of exploitation in the next 30 days; higher than 22% of CVEs (scores of 2026-10-31)
CWE
CWE-755
Published
Modified
Record from
the NVD, synced

Affected

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-hffm-g8v7-wrv7Gogithub.com/caddyserver/caddy/v2<2.11.12.11.1
GO-2026-4539Gogithub.com/caddyserver/caddy/v2<2.11.12.11.1

References

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