WordPress Booking Activities plugin <= 1.18.7.1 - PHP Object Injection vulnerability

{
                    "vendor": "Booking Activities Team",
                    "collectionURL": "https://wordpress.org/plugins",
                    "defaultStatus": "unaffected",
                    "packageName": "booking-activities",
                    "product": "Booking Activities",
                    "versions": [
                        {
                            "lessThanOrEqual": "1.18.7.1",
                            "status": "affected",
                            "version": "n/a",
                            "versionType": "custom",
                            "changes": [
                                {
                                    "at": "1.18.8",
                                    "status": "unaffected"
                                }
                            ]
                        }
                    ]
                }