The imagetruecolortopalette function in ext/gd/gd.c in PHP before 5.6.25 and 7.x before 7.0.10 does not properly validate the number of colors, which allows remote attackers to cause a denial of service (select_colors allocation error and out-of-bounds write) or possibly have unspecified other impact via a large value in the third argument.
[
    {
        "id": "CVE-2016-7126-37a5719d",
        "deprecated": false,
        "signature_version": "v1",
        "signature_type": "Line",
        "target": {
            "file": "ext/gd/gd.c"
        },
        "digest": {
            "line_hashes": [
                "1423120292150075174930076738454850065",
                "130300145211973106865201718306067833063",
                "114156461702382824948003249548063790626",
                "303490943967551169907714634147984509327",
                "6293361012273008610066674150071258249",
                "256829445115917955086582364812563684294",
                "242013541868604548179899499420591114683",
                "265623023047335294992474708258410418763"
            ],
            "threshold": 0.9
        },
        "source": "https://github.com/php/php-src/commit/28022c9b1fd937436ab67bb3d61f652c108baf96"
    },
    {
        "id": "CVE-2016-7126-3fc3a654",
        "deprecated": false,
        "signature_version": "v1",
        "signature_type": "Function",
        "target": {
            "file": "ext/gd/gd.c",
            "function": "PHP_FUNCTION"
        },
        "digest": {
            "function_hash": "325062193662271322533705246369686017798",
            "length": 427.0
        },
        "source": "https://github.com/php/php-src/commit/b6f13a5ef9d6280cf984826a5de012a32c396cd4"
    },
    {
        "id": "CVE-2016-7126-86a80ea0",
        "deprecated": false,
        "signature_version": "v1",
        "signature_type": "Function",
        "target": {
            "file": "ext/gd/gd.c",
            "function": "PHP_FUNCTION"
        },
        "digest": {
            "function_hash": "299071568899511311244268382442547669538",
            "length": 424.0
        },
        "source": "https://github.com/php/php-src/commit/28022c9b1fd937436ab67bb3d61f652c108baf96"
    },
    {
        "id": "CVE-2016-7126-b366f13d",
        "deprecated": false,
        "signature_version": "v1",
        "signature_type": "Line",
        "target": {
            "file": "ext/gd/gd.c"
        },
        "digest": {
            "line_hashes": [
                "126770928617531455781662552752888004178",
                "58257154225830603464532399561035086982",
                "303104341489329115172377785019776380272",
                "199768340353813515127449508570815537454",
                "60772165131950662515060433574910268521",
                "199329124188777352462347349441414973366",
                "284688032288111163403242911724434312678",
                "298899640764450115373202566186393322591",
                "305165316809197570935030791281659852177",
                "311686819433610602352518584518528556735",
                "139124176667830508980884283900175737527",
                "256829445115917955086582364812563684294",
                "242013541868604548179899499420591114683",
                "265623023047335294992474708258410418763",
                "225274767326011585740092982516881541658",
                "257747541152950102621117789614092148544",
                "110970857338032989952000504499983685680",
                "78030080836351927601385261125585094966",
                "76252000699847800932887920885543617170",
                "316829082426001303344116015223512383278",
                "180645478241532636408929824376354052557",
                "264144932551395430872877363754696000201",
                "126432268629793139837764355238639520480"
            ],
            "threshold": 0.9
        },
        "source": "https://github.com/php/php-src/commit/b6f13a5ef9d6280cf984826a5de012a32c396cd4"
    }
]