CVE-2023-51764

Postfix through 3.8.5 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, such as 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.

Affected products

Alt Linux, Almalinux, Linuxmint, Postfix, Red Hat, Red Os, Rocky Linux, Suse

Postfix

< 3.5.23, 3.6.13, 3.7.9, 3.8.4

Fix

Available

CVSS 3.1

5.3 MEDIUM

EPSS

2.6% (84th percentile)

Weakness

CWE-345

NVD status

Modified

Published

2023-12-24