HelloTalk through 3.4.1 stores full-precision GPS coordinates even when the user had intended to share only a country or city. Furthermore, these coordinates are placed into a database on the client of other users. (The client side was changed in 2019 to encrypt that database.)
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:LI:NA:N5.3/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NOther