CVE-2026-32762 (Medium) detected in rack-3.1.16.gem

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
75/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Quiet
Tech stack
ruby
Domain
security

Research direction

Start by inspecting Gemfile.lock and the cached vendor/cache/rack-3.1.16.gem referenced in the report, then trace the rack dependency through rubocop-rails. Update rack to the patched 3.1.21 or 3.2.6 release, refresh the lockfile and cached gem, and confirm the dependency no longer resolves to the vulnerable version.

Written by the indexing model from the issue text.

Description

Mend: dependency security vulnerability

CVE-2026-32762 - Medium Severity Vulnerability

Vulnerable Library - rack-3.1.16.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-3.1.16.gem

Path to dependency file: /Gemfile.lock

Path to vulnerable library: /vendor/cache/rack-3.1.16.gem

Dependency Hierarchy:

  • manageiq-style-1.3.3.gem (Root Library)
    • rubocop-rails-2.32.0.gem
      • ❌ rack-3.1.16.gem (Vulnerable Library)

Found in base branch: master

Vulnerability Details

Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.

Publish Date: 2026-04-02

URL: CVE-2026-32762

CVSS 3 Score Details (4.8)

Base Score Metrics:

  • Exploitability Metrics:
    • Attack Vector: Network
    • Attack Complexity: High
    • Privileges Required: None
    • User Interaction: None
    • Scope: Unchanged
  • Impact Metrics:
    • Confidentiality Impact: Low
    • Integrity Impact: Low
    • Availability Impact: None

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Origin: https://github.com/advisories/GHSA-qfgr-crr9-7r49

Release Date: 2026-04-02

Fix Resolution: rack - 3.2.6,rack - 3.1.21

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Dominant language
Ruby
Stars
30
Forks
27
No merged PRs in 30d

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

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