"In some cases, we share information we store (such as IP addresses) with third parties, such as service providers, consultants, and other agents ("Agents"), for the purposes of operating, enhancing, and improving the Services, and developing new products and services. For example, we may share information with service providers that help us fight spam, payment providers that process your credit and debit card information, customer chat and email support services, analytics providers that help us understand and improve our services, and third party partners that pitch in on our marketing efforts."
Tumblr shares user data broadly with a wide range of third parties including analytics providers (Google Analytics, comScore, Nielsen), marketing partners, and various service providers, creating extensive data exposure.