REDHAT-BUG-2305909: Medium severity dovecot vulnerability
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
Affected Software
Event History
Frequently Asked Questions
What is the severity of REDHAT-BUG-2305909?
The severity of REDHAT-BUG-2305909 is high due to excessive CPU usage when handling a large number of address headers.
How do I fix REDHAT-BUG-2305909?
To fix REDHAT-BUG-2305909, upgrade to the patched version of Dovecot as recommended by Red Hat.
What software is affected by REDHAT-BUG-2305909?
REDHAT-BUG-2305909 affects all versions of Dovecot, particularly in scenarios involving large address headers.
What are the symptoms of REDHAT-BUG-2305909?
The symptoms of REDHAT-BUG-2305909 include significantly increased CPU time and resource consumption when parsing email header lines.
Is there a workaround for REDHAT-BUG-2305909?
A possible workaround for REDHAT-BUG-2305909 is to limit the number of address headers processed in a single email.