CVE-2026-33173 (Medium) detected in activestorage-8.0.4.gem

[mend-bolt-for-github]

CVE-2026-33173 - Medium Severity Vulnerability

Vulnerable Library - activestorage-8.0.4.gem

Attach cloud and local files in Rails applications.

Library home page: https://rubygems.org/gems/activestorage-8.0.4.gem

Path to dependency file: /Gemfile.lock

Path to vulnerable library: /tmp/containerbase/cache/.ruby/cache/activestorage-8.0.4.gem

Dependency Hierarchy:

• gettext_i18n_rails_js-1.3.1.gem (Root Library)
  • rails-8.0.4.gem
    • ❌ activestorage-8.0.4.gem (Vulnerable Library)

Found in base branch: master

Vulnerability Details

Active Storage allows users to attach cloud and local files in Rails applications. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, "DirectUploadsController" accepts arbitrary metadata from the client and persists it on the blob. Because internal flags like "identified" and "analyzed" are stored in the same metadata hash, a direct-upload client can set these flags to skip MIME detection and analysis. This allows an attacker to upload arbitrary content while claiming a safe "content_type", bypassing any validations that rely on Active Storage's automatic content type identification. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

Publish Date: 2026-03-23

URL: CVE-2026-33173

CVSS 3 Score Details (4.3)

Base Score Metrics:

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

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Release Date: 2026-03-23

Fix Resolution: https://github.com/rails/rails.git - v8.1.2.1,https://github.com/rails/rails.git - v8.0.4.1,https://github.com/rails/rails.git - v7.2.3.1

---

Step up your Open Source Security Game with Mend here