CVE-2024-23184 is a vulnerability where processing emails with a very large number of address headers (From, To, Cc, Bcc, etc.) causes excessive CPU usage. For example, parsing 100,000 header lines can take 12 seconds, and 500,000 lines can take up to 18 minutes. This resource exhaustion can be triggered by external actors sending specially crafted emails, potentially leading to denial of service. No public exploits are known, and mitigation involves restricting the number of address headers at the mail transfer agent (MTA) before Dovecot processes the messages.