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CVE-2023-51764

Public on 2023-12-24
Modified on 2024-01-30
Description

Postfix through 3.8.4 allows SMTP smuggling unless configured with smtpd_data_restrictions=reject_unauth_pipelining and smtpd_discard_ehlo_keywords=chunking (or certain other options that exist in recent versions). Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because Postfix supports <LF>.<CR><LF> but some other popular e-mail servers do not. To prevent attack variants (by always disallowing <LF> without <CR>), a different solution is required: the smtpd_forbid_bare_newline=yes option with a Postfix minimum version of 3.5.23, 3.6.13, 3.7.9, 3.8.4, or 3.9.

Severity
Important
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CVSS v3 Base Score
7.5
See breakdown
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Affected Packages

Platform Package Release Date Advisory
Amazon Linux 1 postfix 2024-02-01 19:33 ALAS-2024-1914
Amazon Linux 2 - Core postfix 2024-01-19 01:51 ALAS2-2024-2420
Amazon Linux 2023 postfix 2024-01-19 01:31 ALAS2023-2024-495

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD CVSSv3 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N