CVE-2026-34827 (High) detected in rack-3.2.5.gem
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- Dominant language
- Ruby
- Stars
- 259
- Forks
- 35
- PR merge metrics
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Description
## CVE-2026-34827 - High 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)
- :x: **rack-3.2.5.gem** (Vulnerable Library)
Found in base branch: master
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::Multipart::Parser#handle_mime_head parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 3.1.21 and 3.2.6.
Publish Date: 2026-04-02
URL: CVE-2026-34827
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: High
For more information on CVSS3 Scores, click here.
Type: Upgrade version
Origin: https://github.com/advisories/GHSA-v6x5-cg8r-vv6x
Release Date: 2026-04-02
Fix Resolution: rack - 3.2.6,rack - 3.1.21
***
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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.
Research direction
Start by inspecting the rack entry in /Gemfile.lock and the cached package at /vendor/cache/rack-3.2.5.gem. Update the dependency to a fixed Rack release identified in the issue, then verify that the lockfile and vendor cache no longer contain the vulnerable version and that the project's dependency checks pass.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- ruby
- Domain
- security
- Issue type
- Bug
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Activity status
- Quiet
- Clarity
- Clearly specified
- Newbie friendliness
- 68/100