Vulnerability Details: 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. The main problem is that each header line's address is added to the end of a linked list. This is done by walking the whole linked list, which becomes more inefficient the more addresses there are. Workaround: One can implement restrictions on address headers on MTA component preceding Dovecot. Fix: Install non-vulnerable version of Dovecot. Patch can be found at https://github.com/dovecot/core/compare/8e4c42d%5E...1481c04.patch
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Extended Update Support Via RHSA-2024:6465 https://access.redhat.com/errata/RHSA-2024:6465
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2024:6529 https://access.redhat.com/errata/RHSA-2024:6529