Description
Having a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive. With 100k header lines CPU usage is already 12 seconds, and in a production environment we observed 500k header lines taking 18 minutes to parse. Since this can be triggered by external actors sending emails to a victim, this is a security issue. An external attacker can send specially crafted messages that consume target system resources and cause outage. One can implement restrictions on address headers on MTA component preceding Dovecot. No publicly available exploits are known.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Open-Xchange GmbH OX Dovecot Pro
Default version status: unaffected
0 to ≤ 2.3.21affected