The following two updates has been released for Ubuntu Linux:

USN-3575-2: QEMU regression
USN-3587-1: Dovecot vulnerabilities

USN-3575-2: QEMU regression

==========================================================================
Ubuntu Security Notice USN-3575-2
March 05, 2018

qemu regression
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

USN-3575-1 introduced a regression in QEMU.

Software Description:
- qemu: Machine emulator and virtualizer

Details:

USN-3575-1 fixed vulnerabilities in QEMU. The fix for CVE-2017-11334 caused
a regression in Xen environments. This update removes the problematic fix
pending further investigation.

We apologize for the inconvenience.

Original advisory details:

It was discovered that QEMU incorrectly handled guest ram. A privileged
attacker inside the guest could use this issue to cause QEMU to crash,
resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS
and Ubuntu 16.04 LTS. (CVE-2017-11334)
David Buchanan discovered that QEMU incorrectly handled the VGA device. A
privileged attacker inside the guest could use this issue to cause QEMU to
crash, resulting in a denial of service. This issue was only addressed in
Ubuntu 17.10. (CVE-2017-13672)
Thomas Garnier discovered that QEMU incorrectly handled multiboot. An
attacker could use this issue to cause QEMU to crash, resulting in a denial
of service, or possibly execute arbitrary code on the host. In the default
installation, when QEMU is used with libvirt, attackers would be isolated
by the libvirt AppArmor profile. This issue only affected Ubuntu 14.04 LTS
and Ubuntu 16.04 LTS. (CVE-2017-14167)
Tuomas Tynkkynen discovered that QEMU incorrectly handled VirtFS directory
sharing. An attacker could use this issue to obtain sensitive information
from host memory. (CVE-2017-15038)
Eric Blake discovered that QEMU incorrectly handled memory in the
NBD server. An attacker could use this issue to cause the NBD server to
crash, resulting in a denial of service. This issue only affected Ubuntu
17.10. (CVE-2017-15118)
Eric Blake discovered that QEMU incorrectly handled certain options to the
NBD server. An attacker could use this issue to cause the NBD server to
crash, resulting in a denial of service. This issue only affected Ubuntu
14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-15119)
Daniel Berrange discovered that QEMU incorrectly handled the VNC server. A
remote attacker could possibly use this issue to consume memory, resulting
in a denial of service. This issue was only addressed in Ubuntu 17.10.
(CVE-2017-15124)
Carl Brassey discovered that QEMU incorrectly handled certain websockets. A
remote attacker could possibly use this issue to consume memory, resulting
in a denial of service. This issue only affected Ubuntu 17.10.
(CVE-2017-15268)
Guoxiang Niu discovered that QEMU incorrectly handled the Cirrus VGA
device. A privileged attacker inside the guest could use this issue to
cause QEMU to crash, resulting in a denial of service. (CVE-2017-15289)
Cyrille Chatras discovered that QEMU incorrectly handled certain PS2 values
during migration. An attacker could possibly use this issue to cause QEMU
to crash, resulting in a denial of service, or possibly execute arbitrary
code. This issue only affected Ubuntu 16.04 LTS and Ubuntu 17.10.
(CVE-2017-16845)
It was discovered that QEMU incorrectly handled the Virtio Vring
implementation. An attacker could possibly use this issue to cause QEMU to
crash, resulting in a denial of service. This issue only affected Ubuntu
16.04 LTS and Ubuntu 17.10. (CVE-2017-17381)
Eric Blake discovered that QEMU incorrectly handled certain rounding
operations. An attacker could possibly use this issue to cause QEMU to
crash, resulting in a denial of service. This issue only affected Ubuntu
14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-18043)
Jiang Xin and Lin ZheCheng discovered that QEMU incorrectly handled the
VGA device. A privileged attacker inside the guest could use this issue to
cause QEMU to crash, resulting in a denial of service. (CVE-2018-5683)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 16.04 LTS:
qemu 1:2.5+dfsg-5ubuntu10.24

Ubuntu 14.04 LTS:
qemu 2.0.0+dfsg-2ubuntu1.40

After a standard system update you need to restart all QEMU virtual
machines to make all the necessary changes.

References:
https://usn.ubuntu.com/usn/usn-3575-2
https://usn.ubuntu.com/usn/usn-3575-1
https://launchpad.net/bugs/1752761

Package Information:
https://launchpad.net/ubuntu/+source/qemu/1:2.5+dfsg-5ubuntu10.24
https://launchpad.net/ubuntu/+source/qemu/2.0.0+dfsg-2ubuntu1.40

USN-3587-1: Dovecot vulnerabilities

==========================================================================
Ubuntu Security Notice USN-3587-1
March 05, 2018

dovecot vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 17.10
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in Dovecot.

Software Description:
- dovecot: IMAP and POP3 email server

Details:

It was discovered that Dovecot incorrectly handled parsing certain email
addresses. A remote attacker could use this issue to cause Dovecot to
crash, resulting in a denial of service, or possibly obtain sensitive
information. (CVE-2017-14461)

It was discovered that Dovecot incorrectly handled TLS SNI config lookups.
A remote attacker could possibly use this issue to cause Dovecot to crash,
resulting in a denial of service. (CVE-2017-15130)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 17.10:
dovecot-core 1:2.2.27-3ubuntu1.3

Ubuntu 16.04 LTS:
dovecot-core 1:2.2.22-1ubuntu2.7

Ubuntu 14.04 LTS:
dovecot-core 1:2.2.9-1ubuntu2.4

In general, a standard system update will make all the necessary changes.

References:
https://usn.ubuntu.com/usn/usn-3587-1
CVE-2017-14461, CVE-2017-15130

Package Information:
https://launchpad.net/ubuntu/+source/dovecot/1:2.2.27-3ubuntu1.3
https://launchpad.net/ubuntu/+source/dovecot/1:2.2.22-1ubuntu2.7
https://launchpad.net/ubuntu/+source/dovecot/1:2.2.9-1ubuntu2.4