caddy: Caddy is an extensible server platform that uses TLS by default
CVE-2026-27586 is fixed in 4 products on 1 platform, first by DEBIAN-CVE-2026-27586, released February 24, 2026. It is not reported as exploited. Patch Radar priority: Urgent.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| caddy · Debian 14 | 2.11.2-1 | DEBIAN-CVE-2026-27586 | Feb 24, 2026 |
| caddy · Fedora 43 | 2.10.2-9.fc43 | FEDORA-2026-3DC324BD9A | Jun 23, 2026 |
| caddy-debuginfo · Fedora 43 | 2.10.2-9.fc43 | FEDORA-2026-3DC324BD9A | Jun 23, 2026 |
| caddy-debugsource · Fedora 43 | 2.10.2-9.fc43 | FEDORA-2026-3DC324BD9A | Jun 23, 2026 |
| govulncheck-vulndb · opensuse-leap 15.6 | 0.0.20260226T182644-150000.1.149.1 | SUSE-SU-2026:0757-1 | Mar 3, 2026 |
| govulncheck-vulndb · opensuse-leap 16.0 | 0.0.20260723T184607-160000.1.1 | OPENSUSE-SU-2026:21483-1 | Jul 30, 2026 |
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