CVE-2026-1664

{"id": "CVE-2026-1664", "cveTags": [], "metrics": {"cvssMetricV40": [{"type": "Secondary", "source": "cna@cloudflare.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.9, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/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", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "LOW", "vulnIntegrityImpact": "LOW", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "LOW", "vulnConfidentialityImpact": "LOW", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "published": "2026-02-03T12:16:11.953", "references": [{"url": "https://github.com/cloudflare/agents", "source": "cna@cloudflare.com"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Secondary", "source": "cna@cloudflare.com", "description": [{"lang": "en", "value": "CWE-639"}]}], "descriptions": [{"lang": "en", "value": "Summary\n\nAn Insecure Direct Object Reference has been found to exist in `createHeaderBasedEmailResolver()` function within the Cloudflare Agents SDK. The issue occurs because the `Message-ID` and `References` headers are parsed to derive the target agentName and agentId without proper validation or origin checks, allowing an external attacker with control of these headers to route inbound mail to arbitrary Durable Object instances and namespaces .\n\n\n\n\nRoot cause\n\nThe `createHeaderBasedEmailResolver()` function lacks cryptographic verification or origin validation for the headers used in the routing logic, effectively allowing external input to dictate internal object routing.\n\n\n\n\nImpact\n\nInsecure Direct Object Reference (IDOR) in email routing lets an attacker steer inbound mail to arbitrary Agent instances via spoofed Message-ID.\n\n\n\n\n\nMitigation:\n\n * PR: https://github.com/cloudflare/agents/blob/main/docs/email.md ] provides the necessary architectural context for coding agents to mitigate the issue by refactoring the resolver to enforce strict identity boundaries.\n * Agents-sdk users should upgrade to agents@0.3.7"}, {"lang": "es", "value": "Resumen\n\nSe ha encontrado una Referencia Directa Insegura a Objeto que existe en la funci\u00f3n 'createHeaderBasedEmailResolver()' dentro del SDK de Cloudflare Agents. El problema ocurre porque los encabezados 'Message-ID' y 'References' se analizan para derivar el agentName y el agentId de destino sin la validaci\u00f3n adecuada o comprobaciones de origen, permitiendo a un atacante externo con control de estos encabezados enrutar el correo entrante a instancias y espacios de nombres arbitrarios de Durable Object.\n\nCausa ra\u00edz\n\nLa funci\u00f3n 'createHeaderBasedEmailResolver()' carece de verificaci\u00f3n criptogr\u00e1fica o validaci\u00f3n de origen para los encabezados utilizados en la l\u00f3gica de enrutamiento, permitiendo efectivamente que la entrada externa dicte el enrutamiento interno de objetos.\n\nImpacto\n\nLa Referencia Directa Insegura a Objeto (IDOR) en el enrutamiento de correo electr\u00f3nico permite a un atacante dirigir el correo entrante a instancias arbitrarias de Agent a trav\u00e9s de un Message-ID falsificado.\n\nMitigaci\u00f3n:\n\n * PR: https://github.com/cloudflare/agents/blob/main/docs/email.md ] proporciona el contexto arquitect\u00f3nico necesario para que los agentes de codificaci\u00f3n mitiguen el problema refactorizando el resolvedor para hacer cumplir l\u00edmites de identidad estrictos.\n * Los usuarios del SDK de Agents deben actualizar a agents@0.3.7"}], "lastModified": "2026-04-15T00:35:42.020", "sourceIdentifier": "cna@cloudflare.com"}