[Bug 1721746] [NEW] [If member-email known] Malformed "From:" header accepted -> anyone can post to list.

[René Freund]

*** This bug is a security vulnerability ***

Private security bug reported:

Hello,

because we got some spam from outside, but with email-adress of a list-
member lately, we found after an investigation that the E-Mail Header

From: "memberuseremail@" <memberuserdomain.tld somerandomspamemail.tld>

will be accepted by mailman and posted to the list. So if the spammer
knows a valid member-emailadress it is possible to send emails to the
list.

I don't know if this is fixed already and i have to poke the ubuntu team
instead.

Versions:
Ubuntu 16.04 LTS
Mailman Version: 1:2.1.20-1ubuntu0.1
Postfix Version: 3.1.0-3

** Affects: mailman
     Importance: Undecided
         Status: New


** Tags: email sender

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https://bugs.launchpad.net/bugs/1721746

Title:
  [If member-email known] Malformed "From:" header accepted -> anyone
  can post to list.

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