The Telegram app 7.6.2 for iOS allows remote authenticated users to cause a denial of service (application crash) if the victim pastes an attacker-supplied message (e.g., in the Persian language) into a channel or group. The crash occurs in MtProtoKitFramework. NOTE: the vendor's perspective is that "this behavior can't be considered a vulnerability."

The Terminate Session feature in the Telegram application through 7.2.1 for Android, and through 2.4.7 for Windows and UNIX, fails to invalidate a recently active session.

Telegram before 7.4 (212543) Stable on macOS stores the local passcode in cleartext, leading to information disclosure.

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 2.4.3 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.

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.

The "delete for" feature in Telegram before 5.11 on Android does not delete shared media files from the Telegram Images directory. In other words, there is a potentially misleading UI indication that a sender can remove a recipient's copy of a previously sent image (analogous to supported functionality in which a sender can remove a recipient's copy of a previously sent message).

The Privacy > Phone Number feature in the Telegram app 5.10 for Android and iOS provides an incorrect indication that the access level is Nobody, because attackers can find these numbers via the Group Info feature, e.g., by adding a significant fraction of a region's assigned phone numbers.