UBUNTU-CVE-2026-43971

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Source
https://ubuntu.com/security/CVE-2026-43971
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43971.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-43971
Upstream
Published
2026-08-18T09:17:00Z
Modified
2026-09-16T14:02:03Z
Severity
  • 6.3 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

Improper Encoding or Escaping of Output vulnerability in ninenines cowlib allows Link header directive smuggling via unescaped special characters in cow_link:link/1. cow_link:do_link/1 in cowlib interpolates the target URI, rel value, and attribute keys directly into the serialized Link: header value without escaping or token-grammar validation. A > byte in target prematurely closes the URI slot, allowing an attacker to append additional link entries with attacker-chosen rel directives. A " or \ in rel escapes the quoted string and opens new parameters. Any byte — including whitespace, =, and " — in an attribute key is emitted verbatim. Because browsers act on Link: directives such as rel="preconnect", rel="preload", and rel="prerender", an attacker who can influence these fields in an application that round-trips parsed Link headers through cow_link:link/1 can force victim browsers to make out-of-band connections to attacker-controlled origins. This issue affects cowlib: from 2.9.0 onward.

References

Affected packages

Ubuntu:16.04:LTS
erlang-cowlib

Package

Name
erlang-cowlib
Purl
pkg:deb/ubuntu/erlang-cowlib?arch=source&distro=xenial

Affected ranges

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

Affected versions

1.*
1.3.0-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "erlang-cowlib",
            "binary_version": "1.3.0-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43971.json"
Ubuntu:18.04:LTS
erlang-cowlib

Package

Name
erlang-cowlib
Purl
pkg:deb/ubuntu/erlang-cowlib?arch=source&distro=bionic

Affected ranges

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

Affected versions

1.*
1.3.0-2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "erlang-cowlib",
            "binary_version": "1.3.0-2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43971.json"
Ubuntu:20.04:LTS
erlang-cowlib

Package

Name
erlang-cowlib
Purl
pkg:deb/ubuntu/erlang-cowlib?arch=source&distro=focal

Affected ranges

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

Affected versions

1.*
1.3.0-3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "erlang-cowlib",
            "binary_version": "1.3.0-3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43971.json"
Ubuntu:22.04:LTS
erlang-cowlib

Package

Name
erlang-cowlib
Purl
pkg:deb/ubuntu/erlang-cowlib?arch=source&distro=jammy

Affected ranges

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

Affected versions

1.*
1.3.0-3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "erlang-cowlib",
            "binary_version": "1.3.0-3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43971.json"
Ubuntu:24.04:LTS
erlang-cowlib

Package

Name
erlang-cowlib
Purl
pkg:deb/ubuntu/erlang-cowlib?arch=source&distro=noble

Affected ranges

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

Affected versions

1.*
1.3.0-3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "erlang-cowlib",
            "binary_version": "1.3.0-3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43971.json"
Ubuntu:26.04:LTS
erlang-cowlib

Package

Name
erlang-cowlib
Purl
pkg:deb/ubuntu/erlang-cowlib?arch=source&distro=resolute

Affected ranges

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

Affected versions

1.*
1.3.0-3
1.3.0-3build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "erlang-cowlib",
            "binary_version": "1.3.0-3build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-43971.json"