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Ruby Rack 3.2.x < 3.2.6 Header Injection Vulnerability

medium Nessus Plugin ID 305960

Synopsis

The remote host has an application installed that is affected by a header injection vulnerability.

Description

The version of the Rack Ruby library installed on the remote host is 3.2.0 or later but prior to 3.2.6.
It is, therefore, affected by a header injection vulnerability:

 - Rack::Multipart::Parser unfolds folded multipart part headers incorrectly, preserving embedded CRLF in parsed parameter values instead of removing folded line break. Applications reusing these values in HTTP response headers may be vulnerable to header injection or response splitting. (CVE-2026-26962)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade to Rack version 3.2.6 or later.

See Also

https://github.com/rack/rack/security/advisories/GHSA-rx22-g9mx-qrhv

Plugin Details

Severity: Medium

ID: 305960

File Name: ruby_gem_rack_CVE_2026_26962.nasl

Version: 1.1

Type: Local

Agent: windows, macosx, unix

Family: Misc.

Published: 4/10/2026

Updated: 4/10/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.0

CVSS v2

Risk Factor: Medium

Base Score: 5.8

Vector: CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:N

CVSS Score Source: CVE-2026-26962

CVSS v3

Risk Factor: Medium

Base Score: 4.8

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Vulnerability Information

CPE: cpe:/a:ruby:rack

Required KB Items: Host/ruby/modules/enumerated

Patch Publication Date: 4/2/2026

Vulnerability Publication Date: 4/2/2026

Reference Information

CVE: CVE-2026-26962