{"id":"UBUNTU-CVE-2023-51764","details":"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 \u003cLF\u003e.\u003cCR\u003e\u003cLF\u003e but some other popular e-mail servers do not. To prevent attack variants (by always disallowing \u003cLF\u003e without \u003cCR\u003e), 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.","modified":"2026-04-22T14:15:02.266698Z","published":"2023-12-24T05:15:00Z","related":["USN-6591-1","USN-6591-2"],"upstream":["CVE-2023-51764"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2023-51764"},{"type":"REPORT","url":"https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/"},{"type":"REPORT","url":"https://www.openwall.com/lists/oss-security/2023/12/21/6"},{"type":"REPORT","url":"https://www.postfix.org/smtp-smuggling.html"},{"type":"REPORT","url":"https://www.mail-archive.com/postfix-users@postfix.org/msg100901.html"},{"type":"REPORT","url":"https://www.openwall.com/lists/oss-security/2023/12/22/3"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-6591-1"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-6591-2"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2023-51764"}],"affected":[{"package":{"name":"postfix","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/postfix@2.11.0-1ubuntu1.2+esm3?arch=source&distro=trusty/esm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.11.0-1ubuntu1.2+esm3"}]}],"versions":["2.10.2-1","2.10.2-1build1","2.11.0-1","2.11.0-1ubuntu1","2.11.0-1ubuntu1.2","2.11.0-1ubuntu1.2+esm2"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_name":"postfix","binary_version":"2.11.0-1ubuntu1.2+esm3"},{"binary_name":"postfix-cdb","binary_version":"2.11.0-1ubuntu1.2+esm3"},{"binary_name":"postfix-ldap","binary_version":"2.11.0-1ubuntu1.2+esm3"},{"binary_name":"postfix-mysql","binary_version":"2.11.0-1ubuntu1.2+esm3"},{"binary_name":"postfix-pcre","binary_version":"2.11.0-1ubuntu1.2+esm3"},{"binary_name":"postfix-pgsql","binary_version":"2.11.0-1ubuntu1.2+esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-51764.json"}},{"package":{"name":"postfix","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/postfix@3.1.0-3ubuntu0.4+esm3?arch=source&distro=esm-infra/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.0-3ubuntu0.4+esm3"}]}],"versions":["2.11.3-1ubuntu2","2.11.3-1ubuntu3","3.0.4-1ubuntu1","3.0.4-2","3.0.4-3","3.0.4-5","3.0.4-5build1","3.1.0-3","3.1.0-3ubuntu0.1","3.1.0-3ubuntu0.2","3.1.0-3ubuntu0.3","3.1.0-3ubuntu0.4","3.1.0-3ubuntu0.4+esm2"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_name":"postfix","binary_version":"3.1.0-3ubuntu0.4+esm3"},{"binary_name":"postfix-cdb","binary_version":"3.1.0-3ubuntu0.4+esm3"},{"binary_name":"postfix-ldap","binary_version":"3.1.0-3ubuntu0.4+esm3"},{"binary_name":"postfix-mysql","binary_version":"3.1.0-3ubuntu0.4+esm3"},{"binary_version":"3.1.0-3ubuntu0.4+esm3","binary_name":"postfix-pcre"},{"binary_name":"postfix-pgsql","binary_version":"3.1.0-3ubuntu0.4+esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-51764.json"}},{"package":{"name":"postfix","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/postfix@3.3.0-1ubuntu0.4+esm3?arch=source&distro=esm-infra/bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.3.0-1ubuntu0.4+esm3"}]}],"versions":["3.2.3-1","3.2.3-1build1","3.2.4-1","3.2.5-1","3.2.5-1build1","3.3.0-1","3.3.0-1ubuntu0.1","3.3.0-1ubuntu0.2","3.3.0-1ubuntu0.3","3.3.0-1ubuntu0.4","3.3.0-1ubuntu0.4+esm2"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_name":"postfix","binary_version":"3.3.0-1ubuntu0.4+esm3"},{"binary_name":"postfix-cdb","binary_version":"3.3.0-1ubuntu0.4+esm3"},{"binary_version":"3.3.0-1ubuntu0.4+esm3","binary_name":"postfix-ldap"},{"binary_name":"postfix-lmdb","binary_version":"3.3.0-1ubuntu0.4+esm3"},{"binary_name":"postfix-mysql","binary_version":"3.3.0-1ubuntu0.4+esm3"},{"binary_name":"postfix-pcre","binary_version":"3.3.0-1ubuntu0.4+esm3"},{"binary_name":"postfix-pgsql","binary_version":"3.3.0-1ubuntu0.4+esm3"},{"binary_name":"postfix-sqlite","binary_version":"3.3.0-1ubuntu0.4+esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-51764.json"}},{"package":{"name":"postfix","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/postfix@3.4.13-0ubuntu1.4?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.4.13-0ubuntu1.4"}]}],"versions":["3.4.5-1ubuntu1","3.4.7-1","3.4.7-2","3.4.8-1","3.4.9-1","3.4.10-1","3.4.10-1ubuntu1","3.4.13-0ubuntu1","3.4.13-0ubuntu1.1","3.4.13-0ubuntu1.2","3.4.13-0ubuntu1.3"],"ecosystem_specific":{"binaries":[{"binary_name":"postfix","binary_version":"3.4.13-0ubuntu1.4"},{"binary_name":"postfix-cdb","binary_version":"3.4.13-0ubuntu1.4"},{"binary_name":"postfix-ldap","binary_version":"3.4.13-0ubuntu1.4"},{"binary_name":"postfix-lmdb","binary_version":"3.4.13-0ubuntu1.4"},{"binary_name":"postfix-mysql","binary_version":"3.4.13-0ubuntu1.4"},{"binary_name":"postfix-pcre","binary_version":"3.4.13-0ubuntu1.4"},{"binary_version":"3.4.13-0ubuntu1.4","binary_name":"postfix-pgsql"},{"binary_name":"postfix-sqlite","binary_version":"3.4.13-0ubuntu1.4"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-51764.json"}},{"package":{"name":"postfix","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/postfix@3.6.4-1ubuntu1.3?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.6.4-1ubuntu1.3"}]}],"versions":["3.5.6-1ubuntu2","3.5.13-1ubuntu1","3.5.13-1ubuntu2","3.5.13-1ubuntu3","3.6.3-4ubuntu1","3.6.3-5ubuntu1","3.6.3-5ubuntu2","3.6.4-1ubuntu1","3.6.4-1ubuntu1.1","3.6.4-1ubuntu1.2"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"postfix","binary_version":"3.6.4-1ubuntu1.3"},{"binary_name":"postfix-cdb","binary_version":"3.6.4-1ubuntu1.3"},{"binary_name":"postfix-ldap","binary_version":"3.6.4-1ubuntu1.3"},{"binary_name":"postfix-lmdb","binary_version":"3.6.4-1ubuntu1.3"},{"binary_name":"postfix-mysql","binary_version":"3.6.4-1ubuntu1.3"},{"binary_name":"postfix-pcre","binary_version":"3.6.4-1ubuntu1.3"},{"binary_name":"postfix-pgsql","binary_version":"3.6.4-1ubuntu1.3"},{"binary_name":"postfix-sqlite","binary_version":"3.6.4-1ubuntu1.3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-51764.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}