CVE-2026-34830 (Medium) detected in rack-3.2.1.gem

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## CVE-2026-34830 - Medium Severity Vulnerability
Vulnerable Library - rack-3.2.1.gem

Rack provides a minimal, modular and adaptable interface for developing
web applications in Ruby. By wrapping HTTP requests and responses in
the simplest way possible, it unifies and distills the API for web
servers, web frameworks, and software in between (the so-called
middleware) into a single method call.

Library home page: https://rubygems.org/gems/rack-3.2.1.gem

Path to dependency file: /Gemfile.lock

Path to vulnerable library: /vendor/cache/rack-3.2.1.gem

Dependency Hierarchy:
- manageiq-style-1.5.8.gem (Root Library)
- :x: **rack-3.2.1.gem** (Vulnerable Library)

Found in base branch: master

Vulnerability Details

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Sendfile#map_accel_path interpolates the value of the X-Accel-Mapping request header directly into a regular expression when rewriting file paths for X-Accel-Redirect. Because the header value is not escaped, an attacker who can supply X-Accel-Mapping to the backend can inject regex metacharacters and control the generated X-Accel-Redirect response header. In deployments using Rack::Sendfile with x-accel-redirect, this can allow an attacker to cause nginx to serve unintended files from configured internal locations. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

Publish Date: 2026-04-02

URL: CVE-2026-34830

CVSS 3 Score Details (5.9)

Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: High
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: High
- Integrity Impact: None
- Availability Impact: None

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Origin: https://github.com/advisories/GHSA-qv7j-4883-hwh7

Release Date: 2026-04-02

Fix Resolution: rack - 3.2.6,rack - 2.2.23,rack - 3.1.21

***
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Start with /Gemfile.lock and the cached dependency at /vendor/cache/rack-3.2.1.gem on the master branch. Update Rack to a listed fixed version, then verify the lockfile and cached dependency no longer reference the vulnerable 3.2.1 release.

Written by the indexing model from the issue text.