CVE-2023-51764
MEDIUM 5.3EPSS 2.6%
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.
- CVSS v3.1
- 5.3 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - EPSS
- 2.63% chance of exploitation in the next 30 days, 84th percentile
- Published
- 2023-12-24
- Updated
- 2025-11-04
Proof-of-concept exploits (4)
- duy-31/CVE-2023-5176423★ · 2023-12-26
- eeenvik1/CVE-2023-517644★ · 2023-12-28
- Double-q1015/CVE-2023-517640★ · 2024-01-05
- d4op/CVE-2023-51764-POC1★ · 2024-01-03