Telegram Desktop 2.9.2 contains a denial of service vulnerability that allows attackers to crash the application by sending an oversized message payload. Attackers can generate a 9 million byte buffer and paste it into the messaging interface to trigger an application crash.

A security vulnerability has been detected in Telegram Desktop up to 6.7.5. This vulnerability affects the function RequestButton of the file Telegram/SourceFiles/boxes/urlauthbox.cpp of the component Bot API. The manipulation of the argument loginurl leads to null pointer dereference. It is possible to initiate the attack remotely. The exploit has been disclosed publicly and may be used. There is ongoing doubt regarding the real existence of this vulnerability. Upgrading to version 6.7.6 is able to resolve this issue. Upgrading the affected component is recommended. The vendor provides this rationale for the dispute: "[T]he described scenario does not lead to any security issue or vulnerability, and only causes a one-time crash. In the outlined scenario, the targeted user must perform an active action, which doesn't produce any consequences after the app is relaunched."