“any freely given, specific, informed and unambiguous indication of the data subject's wishes by which he or she, by a statement or by a clear affirmative action, signifies agreement to the processing of personal data relating to him or her”.
Legitimate interests: you can process personal data without consent if you need to do so for a genuine and legitimate reason (including commercial benefit), unless this is outweighed by the individual's rights and interests. Please note however that public authorities are restricted in their ability to use this basis.
Many laws mandate that companies obtain explicit consent from users before collecting, sharing, or selling consumer data for purposes like targeted advertising or personalized marketing. Companies must also be transparent about their data practices, users' rights, and how those rights can be exercised.
Under GDPR, anonymous data is not treated as a personal data, therefore no user consent and no particular protection is required. However, it is very difficult to ensure that data is truly anonymous.
Everyone has the right to the protection of personal data concerning him or her. Such data must be processed fairly for specified purposes and on the basis of the consent of the person concerned, or some other legitimate basis laid down by law.
In summary, you can process personal data without consent if it's necessary for: A contract with the individual: for example, to supply goods or services they have requested, or to fulfil your obligations under an employment contract.
Legitimate interests: you can process personal data without consent if you need to do so for a genuine and legitimate reason (including commercial benefit), unless this is outweighed by the individual's rights and interests. Please note however that public authorities are restricted in their ability to use this basis.
If a data subject withdraws his or her consent, you will be required to stop processing his or her personal data insofar as the processing has been based on consent. Inform data subjects of all bases for processing, so that they will know how the withdrawal of consent will affect the processing of their personal data.
So you not only need to have a lawful basis, but you also need to take extra steps to keep sensitive data safe. But if you haven't got a lawful basis then you shouldn't share it, no matter what extra steps you take or measures you put in place. it's part of a general or unlimited sharing arrangement.