CVE-2026-26961 (Low) detected in rack-3.2.5.gem
Nobody has claimed this yet.
Assessment
- Difficulty
- 1/5
- Estimated time
- Under an hour
- Newbie friendliness
- 72/100
Research direction
Start with Gemfile.lock and vendor/cache/rack-3.2.5.gem on the master branch, and check how this repository records bundled gem versions. Upgrade rack to a listed fixed version and confirm the dependency files no longer reference rack-3.2.5.gem.
Written by the indexing model from the issue text.
Description
CVE-2026-26961 - Low Severity Vulnerability
Vulnerable Library - rack-3.2.5.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-3.2.5.gem
Path to dependency file: /Gemfile.lock
Path to vulnerable library: /vendor/cache/rack-3.2.5.gem
Dependency Hierarchy:
- manageiq-style-1.6.0.gem (Root Library)
- ❌ rack-3.2.5.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::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.
Publish Date: 2026-04-02
URL: CVE-2026-26961
CVSS 3 Score Details (3.7)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: High
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: Low
- Availability Impact: None
Suggested Fix
Type: Upgrade version
Origin: https://github.com/advisories/GHSA-vgpv-f759-9wx3
Release Date: 2026-04-02
Fix Resolution: rack - 3.2.6,rack - 3.1.21,rack - 2.2.23
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- Dominant language
- Ruby
- Stars
- 259
- Forks
- 35
- PR merge metrics
- No merged PRs in 30d
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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