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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-52845 Detail

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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45g CISA-ADP, GitHub, Inc. Exploit  Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-287 Improper Authentication GitHub, Inc.  
CWE-290 Authentication Bypass by Spoofing GitHub, Inc.  
CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') GitHub, Inc.  

Known Affected Software Configurations Switch to CPE 2.2

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Change History

3 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-52845
NVD Published Date:
06/23/2026
NVD Last Modified:
06/26/2026
Source:
GitHub, Inc.