{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-82404", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-08-28T22:00:43.513Z", "datePublished": "2026-09-02T16:30:54.876Z", "dateUpdated": "2026-09-02T16:30:54.876Z"}, "containers": {"cna": {"title": "TOON: Prototype pollution when decoding untrusted TOON input", "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": "LOW", "baseScore": 8.3, "baseSeverity": "HIGH", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L", "version": "3.1"}}], "references": [{"name": "https://github.com/toon-format/toon/security/advisories/GHSA-p95v-992w-h6c3", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/toon-format/toon/security/advisories/GHSA-p95v-992w-h6c3"}, {"name": "https://github.com/toon-format/toon/pull/316", "tags": ["x_refsource_MISC"], "url": "https://github.com/toon-format/toon/pull/316"}, {"name": "https://github.com/toon-format/toon/commit/94a2b7560b2b5ed903a4d466a3bce8b13daa2660", "tags": ["x_refsource_MISC"], "url": "https://github.com/toon-format/toon/commit/94a2b7560b2b5ed903a4d466a3bce8b13daa2660"}, {"name": "https://github.com/toon-format/toon/releases/tag/v2.3.1", "tags": ["x_refsource_MISC"], "url": "https://github.com/toon-format/toon/releases/tag/v2.3.1"}], "affected": [{"vendor": "toon-format", "product": "toon", "versions": [{"version": "< 2.3.1", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-09-02T16:30:54.876Z"}, "descriptions": [{"lang": "en", "value": "TOON is a compact, human-readable serialization of JSON data for LLM prompts. Prior to 2.3.1, decoding attacker-controlled TOON with a __proto__, constructor, or prototype key wrote through the object prototype chain instead of creating an own property, polluting Object.prototype for the runtime. In packages/toon/src/decode/expand.ts, the expandPaths: 'safe' path and insertPathSafe function made dotted keys such as a.__proto__.x the strongest vector, while plain nested objects, tabular rows, quoted keys, and streaming decode were also affected. The encoder also dropped own __proto__ properties and could invoke an inherited setter during normalization. Services that decode untrusted TOON could experience denial of service or, when a suitable downstream gadget is present, remote code execution. This issue is fixed in version 2.3.1."}], "source": {"advisory": "GHSA-p95v-992w-h6c3", "discovery": "UNKNOWN"}}}}

{}

{"affected": [{"affectedData": [{"product": "toon", "vendor": "toon-format", "versions": [{"status": "affected", "version": "< 2.3.1"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "TOON is a compact, human-readable serialization of JSON data for LLM prompts. Prior to 2.3.1, decoding attacker-controlled TOON with a __proto__, constructor, or prototype key wrote through the object prototype chain instead of creating an own property, polluting Object.prototype for the runtime. In packages/toon/src/decode/expand.ts, the expandPaths: 'safe' path and insertPathSafe function made dotted keys such as a.__proto__.x the strongest vector, while plain nested objects, tabular rows, quoted keys, and streaming decode were also affected. The encoder also dropped own __proto__ properties and could invoke an inherited setter during normalization. Services that decode untrusted TOON could experience denial of service or, when a suitable downstream gadget is present, remote code execution. This issue is fixed in version 2.3.1."}], "id": "CVE-2026-82404", "lastModified": "2026-09-02T17:18:00.223", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 8.3, "baseSeverity": "HIGH", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.7, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-09-02T17:18:00.223", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/toon-format/toon/commit/94a2b7560b2b5ed903a4d466a3bce8b13daa2660"}, {"source": "security-advisories@github.com", "url": "https://github.com/toon-format/toon/pull/316"}, {"source": "security-advisories@github.com", "url": "https://github.com/toon-format/toon/releases/tag/v2.3.1"}, {"source": "security-advisories@github.com", "url": "https://github.com/toon-format/toon/security/advisories/GHSA-p95v-992w-h6c3"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-1321"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{}