Issue Title: Incorrectly handling negotiated options of telnet servers #2686 Status: Open Date Opened: Aug 8, 2021 Original Poster: jerrytesting Description: - Vulnerability: In the implementation of telnet servers up to version 3.0 and the latest commit 32b5b17, telnet servers do not correctly handle negotiated options. - RFC Reference: RFC854 specifies that telnet servers must respond with WILL/WONT or DO/DONT for certain commands during negotiation. - Bug Detail: The server implementations put all responses in a fixed-length buffer without checking for success. When the buffer is full, messages can be lost, leading to clients waiting indefinitely. Further Inquiries: - OS-WS (Sep 5, 2021): Asked about plans for fixing the issue. - urlly (Aug 20, 2024): Asked how to reproduce the bug.