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 <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.
How to fix
- postfix postfix3.5.23, 3.6.13, 3.7.9, 3.8.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| postfix postfix | v < 3.5.23, 3.6.0 ≤ v < 3.6.13, 3.7.0 ≤ v < 3.7.9, 3.8.0 ≤ v < 3.8.4 | 3.5.23, 3.6.13, 3.7.9, 3.8.4 |
| fedoraproject fedora | 38, 39 | — |
| redhat enterprise_linux | 8.0, 9.0 | — |
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