A dovecot security update has been released for Debian GNU/Linux 10 to address several vulnerabilities.

DSA 4745-1: dovecot security update

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Debian Security Advisory DSA-4745-1 security@debian.org
  https://www.debian.org/security/ Salvatore Bonaccorso
August 12, 2020   https://www.debian.org/security/faq
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Package : dovecot
CVE ID : CVE-2020-12100 CVE-2020-12673 CVE-2020-12674

Several vulnerabilities have been discovered in the Dovecot email
server.

CVE-2020-12100

Receiving mail with deeply nested MIME parts leads to resource
exhaustion as Dovecot attempts to parse it.

CVE-2020-12673

Dovecot's NTLM implementation does not correctly check message
buffer size, which leads to a crash when reading past allocation.

CVE-2020-12674

Dovecot's RPA mechanism implementation accepts zero-length message,
which leads to assert-crash later on.

For the stable distribution (buster), these problems have been fixed in
version 1:2.3.4.1-5+deb10u3.

We recommend that you upgrade your dovecot packages.

For the detailed security status of dovecot please refer to its security
tracker page at:
  https://security-tracker.debian.org/tracker/dovecot

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://www.debian.org/security/