Out-of-bounds read in TightVNC Viewer ZRLE palette decoding

{
                    "vendor": "GlavSoft",
                    "product": "TightVNC",
                    "platforms": [
                        "Windows"
                    ],
                    "modules": [
                        "TightVNC Viewer (ZRLE decoder)"
                    ],
                    "programFiles": [
                        "ZrleDecoder.cpp"
                    ],
                    "programRoutines": [
                        {
                            "name": "readPaletteRleTile()"
                        },
                        {
                            "name": "readPackedPaletteTile()"
                        }
                    ],
                    "defaultStatus": "unaffected",
                    "versions": [
                        {
                            "version": "0",
                            "lessThan": "2.8.88",
                            "status": "affected",
                            "versionType": "custom"
                        }
                    ]
                }