When returning errors, functions in the net/textproto package would include its input as part of the error. This might allow an attacker to inject misleading content to errors that are printed or logged.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:LA:N5.3/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N