UBUNTU-CVE-2026-52845

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Source
https://ubuntu.com/security/CVE-2026-52845
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-52845.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-52845
Upstream
  • CVE-2026-52845
Published
2026-06-23T18:18:00Z
Modified
2026-07-02T18:03:16.160119088Z
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
  • 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
  • Ubuntu - medium
Summary
[none]
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.

References

Affected packages

Ubuntu:Pro:24.04:LTS / caddy

Package

Name
caddy
Purl
pkg:deb/ubuntu/caddy?arch=source&distro=esm-apps%2Fnoble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.6.2-6
2.6.2-6ubuntu0.24.04.1
2.6.2-6ubuntu0.24.04.2
2.6.2-6ubuntu0.24.04.2+esm1
2.6.2-6ubuntu0.24.04.3
2.6.2-6ubuntu0.24.04.3+esm1
2.6.2-6ubuntu0.24.04.3+esm2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "caddy",
            "binary_version": "2.6.2-6ubuntu0.24.04.3+esm2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-52845.json"

Ubuntu:25.10 / caddy

Package

Name
caddy
Purl
pkg:deb/ubuntu/caddy?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.6.2-9
2.6.2-11
2.6.2-12

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "caddy",
            "binary_version": "2.6.2-12"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-52845.json"

Ubuntu:Pro:26.04:LTS / caddy

Package

Name
caddy
Purl
pkg:deb/ubuntu/caddy?arch=source&distro=esm-apps%2Fresolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.6.2-12
2.6.2-14
2.6.2-14ubuntu0.26.04.1~esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "caddy",
            "binary_version": "2.6.2-14ubuntu0.26.04.1~esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-52845.json"