Telegram has no known backdoors and, even though it is come in for criticism for using proprietary encryption methods instead of open-source ones, those have yet to be compromised. While no messaging app can guarantee a 100% impermeable defense against determined attackers, Telegram is vulnerabilities are few and either theoretical or based on spoof files fooling users into actively enabling an attack.
⃝͋͋͋͋͋͋͋͋͋͋͋͋͋᪥ᭃᴡཻ͎͎ᴀ͎͎̅ྃʟཻ͎͎ʟ͎͎̅ྃᴘཻ͎͎ᴀ͎͎̅ྃᴘཻ͎͎ᴇ͎͎̅ྃʀཻ͎͎s͎͎̅ྃ & ᴘཻ͎͎ʜ͎͎̅ྃᴏཻ͎͎ᴛ͎͎̅ྃᴏཻ͎͎s͎͎̅ྃᬁ࿐ from vn