CVE-2026-52845
EUVD-2026-3855823.06.2026, 18:18
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 (NVD)
| Vendor | Product | Version |
|---|---|---|
| caddyserver | caddy | 𝑥 < 2.11.4 |
𝑥
= Vulnerable software versions
Debian Releases
Ubuntu Releases
Common Weakness Enumeration
- CWE-287 - Improper AuthenticationWhen an actor claims to have a given identity, the software does not prove or insufficiently proves that the claim is correct.
- CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
References