aioSMTP Parameter Injection: Analysis, Fix, and PoC

Vulnerability Key Information Summary Vulnerability Overview Type: SMTP Parameter Injection Description: When the library processes SMTP commands, it does not sufficiently validate address parameters. Attackers can construct addresses containing special characters (e.g., quotes, backslashes, newlines) to inject additional parameters into SMTP commands, which may affect email routing or trigger unexpected behavior. Impact: May cause emails to be routed incorrectly, result in command execution errors, or lead to logic flaws in specific scenarios. Scope of Impact Affected Components: The and functions in the library. Trigger Conditions: When the input address string contains unescaped special characters (such as , , , etc.), may return a parsing result that includes these characters, and fails to escape them correctly, leading to injection. Related Functions: - - Remediation Plan Core Fix: Add validation for the parsed address in ; if it contains illegal characters, raise a . In , properly escape the address (e.g., escape as , and as ). Key Code Changes: - In , if the parsing result contains characters such as , , or , raise a . - In , perform escaping on the address to ensure the generated SMTP commands are safe. POC / Exploitation Code (From Test Cases) ```python Test case: test_semial_reject_command_injection async def test_semial_reject_command_injection(): smtp_client = SMTP() received_commands = [] received_messages = [] with pytest.raises(ValueError): await smtp_client.sendmail( "test@example.com", ["test@example.com"], "Hello World" ) assert received_commands == [] assert received_messages == [] Test case: test_quote_address def test_quote_address(): assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com") == '"a@b@example.com"' assert quote_address("a@b@example.com")

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aioSMTP Parameter Injection: Analysis, Fix, and PoC

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