Threats affecting pkg:github/leshchenko1979/fast-mcp-telegram

fast-mcp-telegram versions prior to 30.1 contain a server-side request forgery (SSRF) vulnerability in the send_message and send_message_to_phone MCP tools. These tools accept files as lists of HTTP(S) URLs, which the server downloads and attaches to outgoing Telegram messages. The URL validation relies on a denylist that checks only the hostname string without DNS resolution, allowing attackers to bypass restrictions and cause the server to fetch resources from internal or private network addresses. This results in a full-read SSRF that can exfiltrate data by returning the fetched content as a Telegram file attachment. The vulnerability is patched in version 30.1.

fast-mcp-telegram is a Telegram MCP Server. Prior to 0.19.1, fast-mcp-telegram validates HTTP Bearer tokens by joining the raw token string into a session-file path. The verifier rejects the exact reserved token telegram, but it does not reject path separators or normalize the path before checking whether the session file exists. A remote HTTP client can therefore authenticate as the default legacy session with a token such as ../fast-mcp-telegram/telegram when the documented default session file ~/.config/fast-mcp-telegram/telegram.session exists. This bypasses the reserved session name control that is intended to prevent HTTP multi-user sessions from colliding with the default stdio or legacy account. With account-prefixed MCP tools enabled, the attacker still sees and calls the prefixed tools for the default account, so the prefix middleware does not stop the session selection bypass. This vulnerability is fixed in 0.19.1.