CVE-2026-34829 (High) detected in rack-3.2.3.gem

Vulnerable Library - rack-3.2.3.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-3.2.3.gem

Sample Path to Dependency File: /Gemfile.lock

Path to vulnerable library: /vendor/cache/rack-3.2.3.gem

Dependency Hierarchy:

• openid_connect-1.4.2.gem (Root Library)
  • rack-oauth2-1.21.3.gem
    • ❌ rack-3.2.3.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 only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

Publish Date: 2026-04-02

URL: CVE-2026-34829

CVSS 3 Score Details (7.5)

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

Suggested Fix

Type: Upgrade version

Origin: https://github.com/advisories/GHSA-8vqr-qjwx-82mw

Release Date: 2026-04-02

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