UltraJSON: Memory Leak in ujson.dump() on Write Failure_CVE-2026-44660

{
    "lastseen": "",
    "description": "UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Prior to 5.12.1, when ujson.dump() writes to a file-like object and the write operation raises an exception, the serialized JSON string object is not decremented, leaking memory. Each failed write operation leaks the full size of the serialized payload. This vulnerability is fixed in 5.12.1.",
    "published": "2026-05-27T20:42:59.830Z",
    "modified": "2026-05-27T20:42:59.830Z",
    "type": "cve",
    "title": "UltraJSON: Memory Leak in ujson.dump() on Write Failure",
    "source": "GitHub_M",
    "references": "https://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xg\nhttps://github.com/ultrajson/ultrajson/commit/82af1d0ac01d09aa40c887b460d44b9d9f4bccd9\nhttps://github.com/ultrajson/ultrajson/releases/tag/5.12.1",
    "id": "CVE-2026-44660",
    "bulletinFamily": "",
    "cwe": [
        "CWE-401"
    ],
    "cvelist": null,
    "sourceData": "ultrajson ultrajson < 5.12.1",
    "sourceHref": "",
    "cvss": {
        "score": 8.7,
        "severity": "HIGH",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "ultrajson",
    "version": "< 5.12.1",
    "vendor": "ultrajson",
    "ai_description": "Memory leak in ujson.dump() when write operation raises an exception",
    "ai_severity": "High",
    "ai_vendor": "ultrajson",
    "ai_product": "UltraJSON",
    "ai_version": "< 5.12.1",
    "ai_score": 8.7
}