CVE-2026-33173: Rails Active Storage has possible content type bypass via metadata in direct uploads
Active Storage’s 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 malicious direct-upload client could set these flags.
References
- github.com/advisories/GHSA-qcfx-2mfw-w4cg
- github.com/rails/rails
- github.com/rails/rails/commit/707c0f1f41f067fdf96d54e99d43b28dfaae7e53
- github.com/rails/rails/commit/8fcb934caadc79c8cc4ce53287046d0f67005b3e
- github.com/rails/rails/commit/d9502f5214e2198245a4c1defe9cd02a7c8057d0
- github.com/rails/rails/releases/tag/v7.2.3.1
- github.com/rails/rails/releases/tag/v8.0.4.1
- github.com/rails/rails/releases/tag/v8.1.2.1
- github.com/rails/rails/security/advisories/GHSA-qcfx-2mfw-w4cg
- nvd.nist.gov/vuln/detail/CVE-2026-33173
Code Behaviors & Features
Detect and mitigate CVE-2026-33173 with GitLab Dependency Scanning
Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Learn more about Dependency Scanning →