Dovecot -- Multiple vulnerabilities

Aki Tuomi reports:

Vulnerability Details:
Sending malformed NOOP command causes crash in submission, submission-login or
lmtp service.

Risk:
Remote attacker can keep submission-login service down, causing denial of
service attack. For lmtp the risk is neglible, as lmtp is usually behind a
trusted MTA.

Steps to reproduce:
Send NOOP EE"FY to submission port, or similarly malformed command.
Vulnerability Details:

Sending command followed by sufficient number of newlines triggers a
use-after-free bug that might crash submission-login, submission or
lmtp service.

Risk:

Remote attacker can keep submission-login service down, causing denial
of service attack. For lmtp the risk is neglible, as lmtp is usually
behind a trusted MTA.

Steps to reproduce:

This can be currently reproduced with ASAN or Valgrind. Reliable way to
crash has not yet been discovered.

Vulnerability Details:
Sending mail with empty quoted localpart causes submission or lmtp component
to crash.

Risk:
Malicious actor can cause denial of service to mail delivery by repeatedly
sending mails with bad sender or recipient address.

Steps to reproduce:
Send mail with envelope sender or recipient as <“”@example.org>.

Workaround:
For submission there is no workaround, but triggering the bug requires valid
credentials.
For lmtp, one can implement sufficient filtering on MTA level to prevent mails
with such addresses from ending up in LMTP delivery.