UBUNTU-CVE-2026-55458

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Source
https://ubuntu.com/security/CVE-2026-55458
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55458.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-55458
Upstream
Published
2026-11-06T00:00:00Z
Modified
2026-11-07T01:45:09Z
Severity
  • 2.9 (Low) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.5, the reverse proxy's finalizeResponse method in modules/caddyhttp/reverseproxy/reverseproxy.go handles an upstream 101 Switching Protocols response before running removeConnectionHeaders and the hopHeaders deletion loop used for ordinary responses. The early return invokes handleUpgradeResponse, which copies the upstream headers to the client and normalizes only WebSocket-specific header names. An attacker who controls or compromises a proxied WebSocket upstream can therefore cause hop-by-hop headers such as Alt-Svc, Keep-Alive, and Proxy-Authenticate, as well as headers named by Connection, to cross the proxy boundary. For HTTP/2 or HTTP/3 extended CONNECT, the upstream 101 response may be represented to the client as an ordinary successful response, increasing the chance that leaked headers are processed. This issue is fixed in version 2.11.5.

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
0 Unknown 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-2026-55458.json"

Ubuntu:26.10 / caddy

Package

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

Affected ranges

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

Affected versions

2.*
2.6.2-14
2.11.4-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "caddy",
            "binary_version": "2.11.4-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55458.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
0 Unknown 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-2026-55458.json"