CVE-2026-52845

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Source
https://cve.org/CVERecord?id=CVE-2026-52845
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52845.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-52845
Aliases
Downstream
Published
2026-06-23T17:52:01.871Z
Modified
2026-07-08T08:10:42.716952552Z
Severity
  • 8.1 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N CVSS Calculator
Summary
Caddy: FastCGI header normalization bypass in `forward_auth copy_headers`
Details

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, forwardauth copyheaders 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 forwardauth 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.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52845.json",
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-287",
        "CWE-290",
        "CWE-444"
    ]
}
References

Affected packages

Git / github.com/caddyserver/caddy

Affected ranges

Type
GIT
Repo
https://github.com/caddyserver/caddy
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
e2eee6a7fce366321294c9c2a79f3146891dcbdf
Database specific 
{
    "cpe": "cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*",
    "source": [
        "AFFECTED_FIELD",
        "CPE_RANGE"
    ],
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "2.11.4"
        }
    ]
}

Affected versions

v2.*
v2.0.0
v2.0.0-beta.13
v2.0.0-beta.14
v2.0.0-beta.15
v2.0.0-beta.16
v2.0.0-beta.17
v2.0.0-beta.18
v2.0.0-beta.19
v2.0.0-beta.20
v2.0.0-beta1
v2.0.0-beta10
v2.0.0-beta11
v2.0.0-beta12
v2.0.0-beta2
v2.0.0-beta3
v2.0.0-beta4
v2.0.0-beta5
v2.0.0-beta6
v2.0.0-beta7
v2.0.0-beta8
v2.0.0-beta9
v2.0.0-rc.1
v2.0.0-rc.2
v2.0.0-rc.3
v2.1.0
v2.1.0-beta.1
v2.1.0-beta.2
v2.1.1
v2.10.0
v2.10.0-beta.1
v2.10.0-beta.2
v2.10.0-beta.3
v2.10.0-beta.4
v2.10.1
v2.10.2
v2.11.0
v2.11.0-beta.1
v2.11.0-beta.2
v2.11.1
v2.11.2
v2.11.3
v2.2.0
v2.2.0-rc.1
v2.2.0-rc.2
v2.2.0-rc.3
v2.2.1
v2.2.3
v2.3.0
v2.3.0-beta.1
v2.3.0-rc.1
v2.3.0-rc.2
v2.4.0
v2.4.0-beta.1
v2.4.0-beta.2
v2.4.0-rc.1
v2.4.1
v2.4.2
v2.4.3
v2.4.4
v2.4.5
v2.4.6
v2.5.0
v2.5.0-beta.1
v2.5.0-rc.1
v2.5.1
v2.5.2
v2.6.0
v2.6.0-beta.1
v2.6.0-beta.2
v2.6.0-beta.3
v2.6.0-beta.4
v2.6.0-beta.5
v2.6.1
v2.6.2
v2.6.3
v2.6.4
v2.7.0
v2.7.0-beta.1
v2.7.0-beta.2
v2.7.1
v2.7.2
v2.7.3
v2.7.4
v2.7.5
v2.8.0
v2.8.0-beta.1
v2.8.0-beta.2
v2.8.0-rc.1
v2.8.1
v2.8.2
v2.8.3
v2.8.4
v2.9.0
v2.9.0-beta.1
v2.9.0-beta.2
v2.9.0-beta.3
v2.9.1

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52845.json"