A security researcher has warned about a security threat posed by the WhatsApp messenger known as Click to Chat this function allows Google to index the phone numbers of users, and all the indexed numbers can be easily found by anyone on the search engine. WhatsApp refused to consider the security flaw as a security flaw, as WhatsApp users themselves chose to make their phone numbers public. The security hole will allow them to easily create well-structured databases of original phone numbers to use them for their personal malicious campaigns. WhatsApp has resolved this issue soon after reported this bug and revealed it online.”]
Source: https://gbhackers.com/whatsapp-bug-leaked-personal-phone-numbers/