CVE-2023-51764 Security feature bypass in n/a

What is CVE-2023-51764?

CVE-2023-51764 is a medium-severity vulnerability in Fedoraproject Fedora, published on 24 Dec 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-345

Which versions are affected by CVE-2023-51764?

It affects 3 products.

Products include Fedoraproject Fedora, Postfix Postfix, Redhat Enterprise Linux.

How do I fix CVE-2023-51764?

Change a configuration setting.

Is CVE-2023-51764 being exploited?

There is no known exploitation of CVE-2023-51764 in the wild and no public exploit code.

Public exploit code: 4 proofs of concept on GitHub.

Other vulnerabilities in Fedoraproject Fedora

• CVE-2024-4577 PHP-CGI OS Command Injection Exploited Critical 9.8
• CVE-2021-39226 Grafana Authentication Bypass Exploited Critical 9.8
• CVE-2019-5544 VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow Exploited Critical 9.8
• CVE-2024-4947 Google Chromium V8 Type Confusion Exploited Critical 9.6
• CVE-2024-4671 Google Chromium Visuals Use-After-Free Exploited Critical 9.6

All Fedoraproject Fedora vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALSA-2024:9243, AZL-32296, AZL-35110, CLSA-2025-1738267482, CLSA-2026-1778834899, CLSA-2026-1778834936 and 13 more.