Bug 2450545 (CVE-2026-33173)

Summary: CVE-2026-33173 Rails: Active Storage: Rails Active Storage: Content type bypass via arbitrary metadata in direct uploads
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akostadi, amasferr, dmayorov, jlledo, jvasik, kaycoth, pantinor, rblanco, tsedmik, vmugicag
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Rails Active Storage. A remote attacker, acting as a direct-upload client, can exploit this vulnerability by manipulating metadata during file uploads. By setting internal flags, the attacker can bypass the system's automatic MIME (Multipurpose Internet Mail Extensions) type detection and analysis. This allows the attacker to upload arbitrary content, potentially circumventing security validations that rely on correct content type identification.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-03-24 00:02:10 UTC
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.