UBUNTU-CVE-2026-26961

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Source

https://ubuntu.com/security/CVE-2026-26961

Import Source

https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26961.json

JSON Data

https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-26961

Upstream

CVE-2026-26961

Downstream

USN-8182-1

Published

2026-04-02T17:16:00Z

Modified

2026-04-17T10:34:14.608248Z

Severity

3.7 (Low) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N CVSS Calculator
Ubuntu - medium

Summary

[none]

Details

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser extracts the boundary parameter from multipart/form-data using a greedy regular expression. When a Content-Type header contains multiple boundary parameters, Rack selects the last one rather than the first. In deployments where an upstream proxy, WAF, or intermediary interprets the first boundary parameter, this mismatch can allow an attacker to smuggle multipart content past upstream inspection and have Rack parse a different body structure than the intermediary validated. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

References

Affected packages

Ubuntu:24.04:LTS

ruby-rack

Package

Name: ruby-rack
Purl: pkg:deb/ubuntu/ruby-rack@2.2.7-1ubuntu0.7?arch=source&distro=noble

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

2.*

2.2.4-3

2.2.7-1

2.2.7-1ubuntu0.1

2.2.7-1ubuntu0.2

2.2.7-1ubuntu0.3

2.2.7-1ubuntu0.4

2.2.7-1ubuntu0.5

2.2.7-1ubuntu0.6

2.2.7-1ubuntu0.7

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "2.2.7-1ubuntu0.7",
            "binary_name": "ruby-rack"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26961.json"

Ubuntu:25.10

ruby-rack

Package

Name: ruby-rack
Purl: pkg:deb/ubuntu/ruby-rack@3.1.16-0.1ubuntu0.3?arch=source&distro=questing

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

2.*

2.2.7-1.1

3.*

3.1.16-0.1

3.1.16-0.1ubuntu0.1

3.1.16-0.1ubuntu0.2

3.1.16-0.1ubuntu0.3

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "3.1.16-0.1ubuntu0.3",
            "binary_name": "ruby-rack"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26961.json"

Ubuntu:Pro:14.04:LTS

ruby-rack

Package

Name: ruby-rack
Purl: pkg:deb/ubuntu/ruby-rack@1.5.2-3+deb8u3ubuntu1~esm11?arch=source&distro=esm-infra-legacy/trusty

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

1.*

1.5.2-1

1.5.2-1ubuntu0.1~esm1

1.5.2-3+deb8u3ubuntu1~esm2

1.5.2-3+deb8u3ubuntu1~esm3

1.5.2-3+deb8u3ubuntu1~esm4

1.5.2-3+deb8u3ubuntu1~esm6

1.5.2-3+deb8u3ubuntu1~esm7

1.5.2-3+deb8u3ubuntu1~esm8

1.5.2-3+deb8u3ubuntu1~esm9

1.5.2-3+deb8u3ubuntu1~esm10

1.5.2-3+deb8u3ubuntu1~esm11

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "1.5.2-3+deb8u3ubuntu1~esm11",
            "binary_name": "librack-ruby"
        },
        {
            "binary_version": "1.5.2-3+deb8u3ubuntu1~esm11",
            "binary_name": "librack-ruby1.8"
        },
        {
            "binary_version": "1.5.2-3+deb8u3ubuntu1~esm11",
            "binary_name": "librack-ruby1.9.1"
        },
        {
            "binary_version": "1.5.2-3+deb8u3ubuntu1~esm11",
            "binary_name": "ruby-rack"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26961.json"

Ubuntu:Pro:16.04:LTS

ruby-rack

Package

Name: ruby-rack
Purl: pkg:deb/ubuntu/ruby-rack@1.6.4-3ubuntu0.2+esm10?arch=source&distro=esm-apps/xenial

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

1.*

1.5.2-4

1.6.4-2

1.6.4-3

1.6.4-3ubuntu0.1

1.6.4-3ubuntu0.2

1.6.4-3ubuntu0.2+esm1

1.6.4-3ubuntu0.2+esm2

1.6.4-3ubuntu0.2+esm4

1.6.4-3ubuntu0.2+esm5

1.6.4-3ubuntu0.2+esm6

1.6.4-3ubuntu0.2+esm7

1.6.4-3ubuntu0.2+esm8

1.6.4-3ubuntu0.2+esm9

1.6.4-3ubuntu0.2+esm10

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "1.6.4-3ubuntu0.2+esm10",
            "binary_name": "ruby-rack"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26961.json"

Ubuntu:Pro:18.04:LTS

ruby-rack

Package

Name: ruby-rack
Purl: pkg:deb/ubuntu/ruby-rack@1.6.4-4ubuntu0.2+esm10?arch=source&distro=esm-apps/bionic

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

1.*

1.6.4-4

1.6.4-4ubuntu0.1

1.6.4-4ubuntu0.2

1.6.4-4ubuntu0.2+esm1

1.6.4-4ubuntu0.2+esm2

1.6.4-4ubuntu0.2+esm4

1.6.4-4ubuntu0.2+esm5

1.6.4-4ubuntu0.2+esm6

1.6.4-4ubuntu0.2+esm7

1.6.4-4ubuntu0.2+esm8

1.6.4-4ubuntu0.2+esm9

1.6.4-4ubuntu0.2+esm10

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "1.6.4-4ubuntu0.2+esm10",
            "binary_name": "ruby-rack"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26961.json"

Ubuntu:Pro:20.04:LTS

ruby-rack

Package

Name: ruby-rack
Purl: pkg:deb/ubuntu/ruby-rack@2.0.7-2ubuntu0.1+esm10?arch=source&distro=esm-apps/focal

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

2.*

2.0.6-3

2.0.7-2

2.0.7-2ubuntu0.1

2.0.7-2ubuntu0.1+esm1

2.0.7-2ubuntu0.1+esm2

2.0.7-2ubuntu0.1+esm3

2.0.7-2ubuntu0.1+esm4

2.0.7-2ubuntu0.1+esm5

2.0.7-2ubuntu0.1+esm6

2.0.7-2ubuntu0.1+esm7

2.0.7-2ubuntu0.1+esm8

2.0.7-2ubuntu0.1+esm9

2.0.7-2ubuntu0.1+esm10

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "2.0.7-2ubuntu0.1+esm10",
            "binary_name": "ruby-rack"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26961.json"

Ubuntu:Pro:22.04:LTS

ruby-rack

Package

Name: ruby-rack
Purl: pkg:deb/ubuntu/ruby-rack@2.1.4-5ubuntu1.2+esm3?arch=source&distro=esm-apps/jammy

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

2.*

2.1.4-3

2.1.4-4

2.1.4-5

2.1.4-5ubuntu1

2.1.4-5ubuntu1+esm2

2.1.4-5ubuntu1+esm3

2.1.4-5ubuntu1+esm4

2.1.4-5ubuntu1+esm5

2.1.4-5ubuntu1.1

2.1.4-5ubuntu1.1+esm1

2.1.4-5ubuntu1.1+esm2

2.1.4-5ubuntu1.2

2.1.4-5ubuntu1.2+esm1

2.1.4-5ubuntu1.2+esm2

2.1.4-5ubuntu1.2+esm3

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "2.1.4-5ubuntu1.2+esm3",
            "binary_name": "ruby-rack"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26961.json"