{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-55091",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-06-16T14:41:54.578Z",
        "datePublished": "2026-09-14T17:26:38.877Z",
        "dateUpdated": "2026-09-14T20:05:59.070Z"
    },
    "containers": {
        "cna": {
            "title": "flat-to-nested: Prototype pollution in flat-to-nested convert() via __proto__ parent/id key",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-915",
                            "lang": "en",
                            "description": "CWE-915: Improperly Controlled Modification of Dynamically-Determined Object Attributes",
                            "type": "CWE"
                        }
                    ]
                },
                {
                    "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": 7.5,
                        "baseSeverity": "HIGH",
                        "confidentialityImpact": "NONE",
                        "integrityImpact": "HIGH",
                        "privilegesRequired": "NONE",
                        "scope": "UNCHANGED",
                        "userInteraction": "NONE",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
                        "version": "3.1"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/joaonuno/flat-to-nested-js/security/advisories/GHSA-hp36-v28f-w3r4",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/joaonuno/flat-to-nested-js/security/advisories/GHSA-hp36-v28f-w3r4"
                },
                {
                    "name": "https://github.com/joaonuno/flat-to-nested-js/commit/680a5ebe1194edda16fa93baaa56ff14fe0e3d7f",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/joaonuno/flat-to-nested-js/commit/680a5ebe1194edda16fa93baaa56ff14fe0e3d7f"
                },
                {
                    "name": "https://github.com/joaonuno/flat-to-nested-js/releases/tag/v1.1.2",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/joaonuno/flat-to-nested-js/releases/tag/v1.1.2"
                }
            ],
            "affected": [
                {
                    "vendor": "joaonuno",
                    "product": "flat-to-nested-js",
                    "versions": [
                        {
                            "version": "< 1.1.2",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-09-14T17:26:38.877Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "flat-to-nested converts a hierarchy from a flat representation to a nested representation. Prior to 1.1.2, FlatToNested.prototype.convert in index.js uses attacker-influenced id and parent record fields directly as keys in the plain temp and pendingChildOf objects. When parent or id is __proto__, temp[parent] can resolve to Object.prototype, and initPush() can write attacker-controlled data to the global children prototype property while existing prototype methods remain intact. Any application that passes attacker-influenced flat records to convert() can therefore expose unrelated objects to polluted inherited state, causing application-logic corruption or denial of service and potentially enabling greater impact when a downstream prototype-pollution gadget is present. The constructor and prototype strings are also unsafe inherited-key values in the same lookup design. This issue is fixed in version 1.1.2."
                }
            ],
            "source": {
                "advisory": "GHSA-hp36-v28f-w3r4",
                "discovery": "UNKNOWN"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-09-14T19:22:11.687253Z",
                                "id": "CVE-2026-55091",
                                "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": "2026-09-14T20:05:59.070Z"
                }
            }
        ]
    }
}