iOS Safari Share Sheet causes potential privacy issue, as it tells website owner when content is shared

Number:rdar://36841950 Date Originated:January 24 2018
Status:Open Resolved:
Product:Safari Product Version:
Classification: Reproducible:Always
As soon as the user hits the share button on mobile Safari, it automatically sends multiple requests to the server, to receive the apple-touch-icon.png logo for the home screen. This is all valid, however it does offer a potential way for website owners to track when their users share content using the Safari share sheet. By using a custom apple-touch-icon.png name for each user (append some kind of user ID), advertising companies could use that to track their users.

I personally don't believe this is a high-impact issue, as the possibilities to abuse it are fairly limited.

Steps to Reproduce:
1. Run a local web server with a simple HTML page
1. Open it on the iOS simulator and hit the share button
1. Look at the server logs and see the requests that were just received

Expected Results:

Actual Results:




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