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CVE-2023-51764

Description

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 . but some other popular e-mail servers do not. To prevent attack variants (by always disallowing without ), 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.

POC

Reference

- https://github.com/duy-31/CVE-2023-51764

- https://github.com/eeenvik1/CVE-2023-51764

- https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/

- https://www.youtube.com/watch?v=V8KPV96g1To

Github

- https://github.com/Double-q1015/CVE-2023-51764

- https://github.com/d4op/CVE-2023-51764-POC

- https://github.com/duy-31/CVE-2023-51764

- https://github.com/eeenvik1/CVE-2023-51764

- https://github.com/fkie-cad/nvd-json-data-feeds

- https://github.com/hannob/smtpsmug

- https://github.com/marklogic/marklogic-docker

- https://github.com/nomi-sec/PoC-in-GitHub