In this area you can find a lot of nonsense we found over the years on the internet. One can only assume why website owners don't ask Telegram (or just visit their page) before publishing such wrong information. Maybe it's laziness by their journalists, just a lack of interest or is it because other messengers invest a lot of money for marketing? It's important to not only check one website these days. If you have any doubts, contact Telegram's support chat via the app settings.
Why I told my friends to stop using WhatsApp and Telegram Link
Telegram is a tricky one since as I mentioned its encryption protocol shows some flaws from an theoretical perspective. In 2015, a security researcher published a paper revealing several major exploits in MTProto and concluded that Telegram shouldn’t have tried to roll their own encryption.
The author dismisses the Telegram protocol as insecure based on a piece of research that doesn't prove this point.
Update: The blog author already corrected his text and linked to Telegram's statement.
RT Kaspersky uncovers Telegram vulnerability that allows malicious crypto-mining Link
Cybersecurity firm Kaspersky Lab has uncovered a vulnerability in the Telegram desktop app which allows the social messaging app to be exploited for mining cryptocurrencies.
They make it sound like it was just discovered. The issue was discovered 2017 and fixed immediately by Telegram developers (verifiable in their public app source code). Also for this to work you’d have to click on a malicious file looking like an image sent as a file (without a preview). Windows (the only affected system) would show a warning, asking if you want to "run this software".
A look at how private messengers handle key changes Link
The author of the Medium post seems to have little understanding of how things work on Telegram.
Telegram Statement regarding key changes.
This man is behind Telegram Messenger On Twitter they used the following description: "Telegram founder Pavel Durov praises security and privacy. Users trust him, but experts warn - even before his new cryptocurrency"
The author claims on the German SZ news website that Group Chats are not encrypted, which is of course not true, since all chats are heavily encrypted.
Update 27/03/18: Still not corrected on SZ website.
Whatsapp Alternative Telegram reaches 200 million users They write on their website that chats are stored unencrypted on the servers.
Absolutely nonsense. Telegram's privacy page clearly states: "All data is stored heavily encrypted and the encryption keys in each case are stored in several other DCs in different jurisdictions. This way local engineers or physical intruders cannot get access to user data."
FSB hacked Telegram Link
A scare story first found in January, 2016, claiming that some unnamed "ex-operative" heard from some other unnamed "agent" that the FSB has "cracked" Telegram back in summer 2015. This story is a part of an "intelligence report" that has been touring the journalistic circles since June 2016.
Telegram's statement: Link