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             AUSCERT External Security Bulletin Redistribution

                              ESB-2021.1834.2
                      USN-4969-1: DHCP vulnerability
                                8 June 2021

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           isc-dhcp
Publisher:         Ubuntu
Operating System:  Ubuntu
                   UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-25217  

Original Bulletin: 
   https://ubuntu.com/security/notices/USN-4969-1
   https://ubuntu.com/security/notices/USN-4969-2
   https://ubuntu.com/security/notices/USN-4969-3

Comment: This bulletin contains three (3) Ubuntu security advisories.

Revision History:  June  8 2021: Regression fix detailed in USN-4969-3
                   May  28 2021: Initial Release

- --------------------------BEGIN INCLUDED TEXT--------------------

USN-4969-1: DHCP vulnerability
27 May 2021

DHCP could be made to crash if it received specially crafted network
traffic.
Releases

  o Ubuntu 21.04
  o Ubuntu 20.10
  o Ubuntu 20.04 LTS
  o Ubuntu 18.04 LTS

Packages

  o isc-dhcp - DHCP server and client

Details

Jon Franklin and Pawel Wieczorkiewicz discovered that DHCP incorrectly
handled lease file parsing. A remote attacker could possibly use this issue
to cause DHCP to crash, resulting in a denial of service.

Update instructions

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

Ubuntu 21.04

  o isc-dhcp-server - 4.4.1-2.2ubuntu6.1
  o isc-dhcp-client - 4.4.1-2.2ubuntu6.1

Ubuntu 20.10

  o isc-dhcp-server - 4.4.1-2.1ubuntu10.1
  o isc-dhcp-client - 4.4.1-2.1ubuntu10.1

Ubuntu 20.04

  o isc-dhcp-server - 4.4.1-2.1ubuntu5.20.04.2
  o isc-dhcp-client - 4.4.1-2.1ubuntu5.20.04.2

Ubuntu 18.04

  o isc-dhcp-server - 4.3.5-3ubuntu7.3
  o isc-dhcp-client - 4.3.5-3ubuntu7.3

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

References

  o CVE-2021-25217

Related notices

  o USN-4969-2 : isc-dhcp-client, isc-dhcp-server, isc-dhcp


- ------------------------------------------------------------------------------


USN-4969-2: DHCP vulnerability
27 May 2021

DHCP could be made to crash if it received specially crafted network
traffic.
Releases

  o Ubuntu 16.04 ESM
  o Ubuntu 14.04 ESM

Packages

  o isc-dhcp - DHCP server and client

Details

USN-4969-1 fixed a vulnerability in DHCP. This update provides
the corresponding update for Ubuntu 14.04 ESM and 16.04 ESM.

Original advisory details:

Jon Franklin and Pawel Wieczorkiewicz discovered that DHCP incorrectly
handled lease file parsing. A remote attacker could possibly use this issue
to cause DHCP to crash, resulting in a denial of service.

Update instructions

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

Ubuntu 16.04

  o isc-dhcp-server - 4.3.3-5ubuntu12.10+esm1
    Available with UA Infra or UA Desktop
  o isc-dhcp-client - 4.3.3-5ubuntu12.10+esm1
    Available with UA Infra or UA Desktop

Ubuntu 14.04

  o isc-dhcp-server - 4.2.4-7ubuntu12.13+esm1
    Available with UA Infra or UA Desktop
  o isc-dhcp-client - 4.2.4-7ubuntu12.13+esm1
    Available with UA Infra or UA Desktop

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

References

  o CVE-2021-25217

Related notices

  o USN-4969-1 : isc-dhcp-client, isc-dhcp, isc-dhcp-server


- ------------------------------------------------------------------------------

USN-4969-3: DHCP regression
07 June 2021

USN-4969-1 introduced a regression in DHCP.
Releases

  o Ubuntu 21.04

Packages

  o isc-dhcp - DHCP server and client

Details

USN-4969-1 fixed a vulnerability in DHCP. The package for Ubuntu 21.04
introduced a regression causing it to reject certain valid configuration
files. This update fixes the problem.

We apologize for the inconvenience.

Original advisory details:

Jon Franklin and Pawel Wieczorkiewicz discovered that DHCP incorrectly
handled lease file parsing. A remote attacker could possibly use this issue
to cause DHCP to crash, resulting in a denial of service.

Update instructions

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

Ubuntu 21.04

  o isc-dhcp-client - 4.4.1-2.2ubuntu6.2
  o isc-dhcp-server - 4.4.1-2.2ubuntu6.2

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

References

  o https://launchpad.net/bugs/1930917

- --------------------------END INCLUDED TEXT--------------------

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