"We disclose a novel tracking method by Meta and Yandex potentially affecting billions of Android users. We found that native Android apps—including Facebook, Instagram, and several Yandex apps including Maps and Browser—silently listen on fixed local ports for tracking purposes. " https://localmess.github.io/ via https://arstechnica.com/security/2025/06/meta-and-yandex-are-de-anonymizing-android-users-web-browsing-identifiers/ "Meta and Yandex are de-anonymizing Android users’ web browsing identifiers"