CVE-2026-52845
HIGH EPSS 10.9%
Published Jun 23, 20261w ago · Modified Jun 24, 20261w ago
8.1 CVSS 3.1
Published Jun 23, 2026 1w ago
Last Modified Jun 24, 2026 1w ago
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.
CVSS Details
Base Score
Exploitability
Impact
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Attack Vector Network
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability None
Threat Intelligence
EPSS Exploit Probability
10.9% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available
Weaknesses 3
CWE-287 Improper Authentication Authentication
CWE-290
CWE-444
References 1
- github.com https://github.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45g
Remediation
No remediation data recorded yet
Check vendor advisories and the NVD entry for patch availability.