UBUNTU-CVE-2026-27586

See a problem?
Please try reporting it to the source first.
Source
https://ubuntu.com/security/CVE-2026-27586
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27586.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-27586
Upstream
Published
2026-02-24T17:29:00Z
Modified
2026-02-28T06:17:18.555269Z
Severity
  • 8.8 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P CVSS Calculator
  • 9.1 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/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 version 2.11.1, two swallowed errors in ClientAuthentication.provision() cause mTLS client certificate authentication to silently fail open when a CA certificate file is missing, unreadable, or malformed. The server starts without error but accepts any client certificate signed by any system-trusted CA, completely bypassing the intended private CA trust boundary. Any deployment using trusted_ca_cert_file or trusted_ca_certs_pem_files for mTLS will silently degrade to accepting any system-trusted client certificate if the CA file becomes unavailable. This can happen due to a typo in the path, file rotation, corruption, or permission changes. The server gives no indication that mTLS is misconfigured. Version 2.11.1 fixes the vulnerability.

References

Affected packages

Ubuntu:Pro:24.04:LTS / caddy

Package

Name
caddy
Purl
pkg:deb/ubuntu/caddy@2.6.2-6ubuntu0.24.04.3+esm1?arch=source&distro=esm-apps/noble

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

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "2.6.2-6ubuntu0.24.04.3+esm1",
            "binary_name": "caddy"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27586.json"

Ubuntu:25.10 / caddy

Package

Name
caddy
Purl
pkg:deb/ubuntu/caddy@2.6.2-12?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_version": "2.6.2-12",
            "binary_name": "caddy"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27586.json"