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Security Bug CVE-2019-20790: OpenDMARC can be bypassed when it's used with pypolicyd-spf  #49

@chenjj

Description

@chenjj

I cannot find a private address for reporting security bugs, so I have to post it here.

If a mail server uses both OpenDMARC and pypolicyd-spf, its SPF and DMARC authentication can be bypassed with the following message:

HELO: attacker.com
MAIL FROM: <[email protected]>
...
From: <[email protected]>
...
  • pypolicyd-spf uses the HELO identifier and generates the following message:
    Received-SPF: Pass (helo) identity=helo; client-ip=1.2.3.4; helo=attack.com; [email protected];
  • OpenDMARC uses the MAIL FROM identifier to check alignment with the From header.

Given the popularity of OpenDMARC and pypolicyd-spf, this bug may affect many online services. Hope you can fix it soon.

Detailed reproduce steps at:
https://sourceforge.net/p/opendmarc/tickets/235/

I have also reported it to pypolicyd-spf:
https://bugs.launchpad.net/pypolicyd-spf/+bug/1838816

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