CVE-2025-61771 (High) detected in rack-2.2.9.gem

Vulnerable Library - rack-2.2.9.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-2.2.9.gem

Path to dependency file: /Gemfile.lock

Path to vulnerable library: /home/wss-scanner/.gem/ruby/3.2.0/cache/rack-2.2.9.gem

Dependency Hierarchy:

• rack-test-2.1.0.gem (Root Library)
  • ❌ rack-2.2.9.gem (Vulnerable Library)

Found in base branch: master

Vulnerability Details

Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, ``Rack::Multipart::Parser"stores non-file form fields (parts without a"filename") entirely in memory as Ruby "String"objects. A single large text field in a multipart/form-data request (hundreds of megabytes or more) can consume equivalent process memory, potentially leading to out-of-memory (OOM) conditions and denial of service (DoS). Attackers can send large non-file fields to trigger excessive memory usage. Impact scales with request size and concurrency, potentially leading to worker crashes or severe garbage-collection overhead. All Rack applications processing multipart form submissions are affected. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a reasonable size cap for non-file fields (e.g., 2 MiB). Workarounds include restricting maximum request body size at the web-server or proxy layer (e.g., Nginx"client_max_body_size`) and validating and rejecting unusually large form fields at the application level.
Mend Note: The description of this vulnerability differs from MITRE.

Publish Date: 2025-10-07

URL: CVE-2025-61771

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-w9pc-fmgc-vxvw

Release Date: 2025-10-07

Fix Resolution: rack - 3.2.2,rack - 2.2.19,rack - 3.1.17,https://github.com/rack/rack.git - v2.2.19,https://github.com/rack/rack.git - v3.2.2,https://github.com/rack/rack.git - v3.1.17