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CVE-2026-52845

HIGH
8.1
CVSS 3.1
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.

Metadata

CVE ID
CVE-2026-52845
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-06-08 18:41 UTC
Published
2026-06-23 17:52 UTC
Last updated
2026-06-23 17:52 UTC
Primary CWE
CWE-287
CWE-287: Improper Authentication
Vendor / Product
caddyserver / caddy
Sources
cve.org  ·  NVD

Severity & Metrics

8.1 HIGH CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Affected products (1)
VendorProductPlatformVersions
caddyserver caddy — < 2.11.4
Weakness (CWE)
CWESourceDescription
CWE-287 cna CWE-287: Improper Authentication
CWE-290 cna CWE-290: Authentication Bypass by Spoofing
CWE-444 cna CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CVSS scores (1)
ScoreSeverityVersionSourceVector
8.1 HIGH 3.1 cna CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
References (1)
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