Telegram Desktop (aka tdesktop) 1.3.14, and Telegram 3.3.0.0 WP8.1 on Windows, leaks end-user public and private IP addresses during a call because of an unsafe default behavior in which P2P connections are accepted from clients outside of the My Contacts list.
telegram
CVE-2018-17613
Telegram Desktop (aka tdesktop) 1.3.16 alpha, when “Use proxy” is enabled, sends credentials and application data in cleartext over the SOCKS5 protocol.
CVE-2018-17231
** DISPUTED ** Telegram Desktop (aka tdesktop) 1.3.14 might allow attackers to cause a denial of service (assertion failure and application exit) via an “Edit color palette” search that triggers an “index out of range” condition. NOTE: this issue is disputed by multiple third parties because the described attack scenario does not cross a privilege boundary.
CVE-2020-25824
Telegram Desktop through 2.4.3 does not require passcode entry upon pushing the Export key within the Export Telegram Data wizard. The threat model is a victim who has voluntarily opened Export Wizard but is then distracted. An attacker then approaches the unattended desktop and pushes the Export key. This attacker may consequently gain access to all chat conversation and media files.
CVE-2020-17448
Telegram Desktop through 2.1.13 allows a spoofed file type to bypass the Dangerous File Type Execution protection mechanism, as demonstrated by use of the chat window with a filename that lacks an extension.
CVE-2020-12474
Telegram Desktop through 2.0.1, Telegram through 6.0.1 for Android, and Telegram through 6.0.1 for iOS allow an IDN Homograph attack via Punycode in a public URL or a group chat invitation URL.