Telegram before 7.4 (212543) Stable on macOS stores the local copy of self-destructed messages in a sandbox path, leading to sensitive information disclosure.
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.
The Telegram application through 5.12 for Android, when Show Popup is enabled, might allow physically proximate attackers to bypass intended restrictions on message reading and message replying. This might be interpreted as a bypass of the passcode feature.
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.