SB2020042431 - Insufficient verification of data authenticity in Postfix

Description

This security bulletin contains information about 1 security vulnerability.

1) Insufficient verification of data authenticity (CVE-ID: CVE-2020-12063)

The vulnerability allows a remote non-authenticated attacker to manipulate data.

** DISPUTED ** A certain Postfix 2.10.1-7 package could allow an attacker to send an email from an arbitrary-looking sender via a homoglyph attack, as demonstrated by the similarity of xcexbf to the 'o' character. This is potentially relevant when the /etc/postfix/sender_login feature is used, because a spoofed outbound message that uses a configured sender address is blocked with a "Sender address rejected: not logged in" error message, but a spoofed outbound message that uses a homoglyph of a configured sender address is not blocked. NOTE: some third parties argue that any missed blocking of spoofed outbound messages - except for exact matches to a sender address in the /etc/postfix/sender_login file - is outside the design goals of Postfix and thus cannot be considered a Postfix vulnerability.

Remediation

Install update from vendor's website.

References

• https://www.openwall.com/lists/oss-security/2020/04/23/12
• https://www.openwall.com/lists/oss-security/2020/04/23/3