At summer I decided to test Facebook Messenger for MacOS. Grepped all urls from code and started to analyze them. Quickly I noticed few urls on image with "access_token" value: Cool! Interesting is this token still valid? I opened https://developers.facebook.com/tools/debug/accesstoken/?access_token= and got confirmation: the token is valid! I stopped experiments and rapidly sent report to Facebook Team. All time before bounty decision I hoped that this token had some extra internal permissions. Unfortunately for me looks like it was just normal token, probably from Facebook employee, without any extra access. I think some software developer placed such link by mistake inside the app and it went over whole world)) So, be careful and attentive when you investigate hardcoded data inside apps ;) Facebook Messenger v. 97.11.116 (97.11.116.283083801) for MacOS Submitted: 27.07.2021 10:08AM Triaged: 27.07.2021 12:36AM Fixed: 27.07.2021 12:45AM (token became invalid, may be system...