In this vulnerability disclosure report, we discuss details of 5Ghoul – a family of implementation-level 5G vulnerabilities. Such a family of vulnerabilities are present in the firmware implementation of 5G mobile network modems from major chipset vendors i.e., Qualcomm and MediaTek. Consequently, many 5G-capable commercial products such as smartphones, Customer-premises Equipment (CPE) routers and USB modems are potentially impacted due to the employment of vulnerable 5G modems in such products. In total, we have found 12 new vulnerabilities (14 total), out of which 10 affect 5G modems from Qualcomm and MediaTek. More importantly, three of these ten vulnerabilities are confirmed to have high severity. We also wrote a scraper to send crafted queries to https://www.kimovil.com/en/ and to have an estimate on the number of smartphone models affected due to these vulnerabilities. We found over 710 smartphone models that are currently in the market to be affected. We emphasize that the actual number of affected models might be more, as firmware code is often shared across different modem versions. In this disclosure report, we also demonstrate the exploitation of 5Ghoul vulnerabilities to drop and freeze 5G connection on smartphones and CPE routers. We also show downgrade attacks across multiple smartphones that result in downgrading the 5G connection to 4G.