8.1
High
CVE-2026-52845 Caddy is an extensible server platform that uses TLS by default
Description
Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, forward_auth copy_headers deletes the exact client-supplied identity header before copying the trusted value from the auth gateway. But when the request later goes through php_fastcgi, Caddy normalizes HTTP headers into CGI variables by replacing - with _. This lets a client send an underscore alias that survives the forward_auth delete step but becomes the same PHP/FastCGI variable. Result: a remote client can inject or sometimes override identity/group headers trusted by PHP/FastCGI applications behind Caddy. This vulnerability is fixed in 2.11.4.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| caddy 2.11 | earliest → < 2.11.4 | 2.11.4 |
| Red Hat Hardened Images | Versions not published |
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The 17 CVEs of caddy →
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