All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
It is impermissible to take someone's picture or post it on social media without their permission and consent.
Shaykh ʻAbd Ar-Rahmaan Al-Barraak, may Allah protect him, while listing the consequent Shariah violations of photography in general, wrote:
"Taking photos of people without their consent is a violation of their privacy rights, and the evil is graver when these photos are released and displayed to people. These photos could be of a woman, and it is prohibited to take photos of her or display them to others even if she gave her consent; this may cause her divorce if she is married or drive the suitors away from her if she is unmarried, in addition to the evil of having non-Mahram (marriageable) men looking at her photos. Another example is taking photos of someone without their consent in a private gathering or taking photos of their house, furniture, or children and the like."
Allah knows best.