{"id":"AZL-35110","summary":"CVE-2023-51764 affecting package postfix for versions less than 3.9.0-1","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":"2026-04-21T04:27:50.274755Z","published":"2023-12-24T05:15:08Z","upstream":["CVE-2023-51764"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-51764"}],"affected":[{"package":{"name":"postfix","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/postfix"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.9.0-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-35110.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"}]}