{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-31865", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-03-09T19:02:25.013Z", "datePublished": "2026-03-18T02:50:55.403Z", "dateUpdated": "2026-03-18T18:39:09.024Z"}, "containers": {"cna": {"title": "Elysia Cookie Value Prototype Pollution", "problemTypes": [{"descriptions": [{"cweId": "CWE-1321", "lang": "en", "description": "CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/elysiajs/elysia/security/advisories/GHSA-8hq9-phh3-p2wp", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/elysiajs/elysia/security/advisories/GHSA-8hq9-phh3-p2wp"}, {"name": "https://github.com/elysiajs/elysia/commit/e9d6b1743fa7368ef942dce181f6a089757f6aab", "tags": ["x_refsource_MISC"], "url": "https://github.com/elysiajs/elysia/commit/e9d6b1743fa7368ef942dce181f6a089757f6aab"}], "affected": [{"vendor": "elysiajs", "product": "elysia", "versions": [{"version": "< 1.4.27", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-03-18T02:50:55.403Z"}, "descriptions": [{"lang": "en", "value": "Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to version 1.4.27, an Elysia cookie can be overridden by prototype pollution , eg. `__proto__`. This issue is patched in 1.4.27. As a workaround, use t.Cookie validation to enforce validation value and/or prevent iterable over cookie if possible."}], "source": {"advisory": "GHSA-8hq9-phh3-p2wp", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-03-18T18:36:47.933361Z", "id": "CVE-2026-31865", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-03-18T18:39:09.024Z"}}]}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to version 1.4.27, an Elysia cookie can be overridden by prototype pollution , eg. `__proto__`. This issue is patched in 1.4.27. As a workaround, use t.Cookie validation to enforce validation value and/or prevent iterable over cookie if possible."}, {"lang": "es", "value": "Elysia es un framework de Typescript para la validaci\u00f3n de solicitudes, inferencia de tipos, documentaci\u00f3n OpenAPI y comunicaci\u00f3n cliente-servidor. Antes de la versi\u00f3n 1.4.27, una cookie de Elysia pod\u00eda ser sobrescrita mediante contaminaci\u00f3n de prototipos, p. ej. `__proto__`. Este problema est\u00e1 parcheado en la versi\u00f3n 1.4.27. Como soluci\u00f3n alternativa, use la validaci\u00f3n t.Cookie para forzar el valor de validaci\u00f3n y/o evitar la iteraci\u00f3n sobre la cookie si es posible."}], "id": "CVE-2026-31865", "lastModified": "2026-03-18T14:52:44.227", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 2.5, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-03-18T04:17:19.393", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/elysiajs/elysia/commit/e9d6b1743fa7368ef942dce181f6a089757f6aab"}, {"source": "security-advisories@github.com", "url": "https://github.com/elysiajs/elysia/security/advisories/GHSA-8hq9-phh3-p2wp"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-1321"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,1.4.27)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "elysia", "source": "cna", "vendor": "elysiajs"}, "product": "elysia", "vendor": "elysiajs"}], "created": "2026-03-18T10:41:59.419669+00:00", "updated": "2026-03-18T10:41:59.419752+00:00", "vendors": ["elysiajs", "elysiajs$PRODUCT$elysia"]}