In ConvertX before 0.19.0, converters/calibre.ts does not block recipe files, and instead passes them to the ebook-convert program from Calibre. This affects executable code in a .recipe or .downloaded_recipe file.

{
                    "defaultStatus": "unaffected",
                    "product": "ConvertX",
                    "vendor": "C4illin",
                    "versions": [
                        {
                            "lessThan": "0.19.0",
                            "status": "affected",
                            "version": "0",
                            "versionType": "semver"
                        }
                    ]
                }