A reordering issue exists in Telegram before 7.8.1 for Android, Telegram before 7.8.3 for iOS, and Telegram Desktop before 2.8.8. An attacker can cause the server to receive messages in a different order than they were sent a client.

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.

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.

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.

Telegram Desktop before 1.5.12 on Windows, and the Telegram applications for Android, iOS, and Linux, is vulnerable to an IDN homograph attack when displaying messages containing URLs. This occurs because the application produces a clickable link even if (for example) Latin and Cyrillic characters exist in the same domain name, and the available font has an identical representation of characters from different alphabets.

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 Desktop (aka tdesktop) 1.3.16 alpha, when "Use proxy" is enabled, sends credentials and application data in cleartext over the SOCKS5 protocol.

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

Telegram Desktop 0.10.19 uses 0755 permissions for $HOME/.TelegramDesktop, which allows local users to obtain sensitive authentication information via standard filesystem operations.