Telegram-desktop is the official desktop client for Telegram.
During the navigation of my filesystem I found the .TelegramDesktop with 755 permission:
drwxr-xr-x 4 ago ago 4096 nov 23 14:30 .TelegramDesktop
At least from 0.10.19 to 1.0.29
This bug was discovered by Agostino Sarubbo of Gentoo.
2016-11-23: bug discovered and reported to upstream
2017-05-01: blog post about the issue
2017-05-01: CVE assigned