What’s Vulnerable › Vulnerabilities

CVE-2020-12063

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-04-24 · updated 2026-06-17

Description

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 \xce\xbf 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

Affected products

• Postfix: 2.10.1

References

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

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