[USN-3586-2] DHCP vulnerabilities


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Ubuntu Security Notice USN-3586-2
May 28, 2018

isc-dhcp vulnerabilities
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
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A security issue affects these releases of Ubuntu and its derivatives:

– Ubuntu 12.04 ESM

Summary:

Several security issues were fixed in DHCP.

Software Description:
– isc-dhcp: DHCP server and client

Details:

USN-3586-1 fixed a vulnerability in DHCP. This update provides
the corresponding update for Ubuntu 12.04 ESM.

Original advisory details:

=C2=A0Felix Wilhelm discovered that the DHCP client incorrectly handled
=C2=A0certain malformed responses. A remote attacker could use this issue t=
o
=C2=A0cause the DHCP client to crash, resulting in a denial of service, or
=C2=A0possibly execute arbitrary code. In the default installation,
=C2=A0attackers would be isolated by the dhclient AppArmor profile.=C2=A0
=C2=A0(CVE-2018-5732)

=C2=A0Felix Wilhelm discovered that the DHCP server incorrectly handled
=C2=A0reference counting. A remote attacker could possibly use this issue t=
o
=C2=A0cause the DHCP server to crash, resulting in a denial of service.
=C2=A0(CVE-2018-5733)

Update instructions:

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

Ubuntu 12.04 ESM:
=C2=A0 isc-dhcp-client=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A04.1.ESV-R4-0ubuntu5.13
=C2=A0 isc-dhcp-relay=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A04.1.ESV-R4-0ubuntu5.1=
3
=C2=A0 isc-dhcp-server=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A04.1.ESV-R4-0ubuntu5.13
=C2=A0 isc-dhcp-server-ldap=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A04.1.ESV-R4-0ubuntu5.13

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

References:
=C2=A0 https://usn.ubuntu.com/usn/usn-3586-2
=C2=A0 https://usn.ubuntu.com/usn/usn-3586-1
=C2=A0 CVE-2018-5732, CVE-2018-5733
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