There had existed in one of the ISC BIND libraries a bug in a function that
was used by dhcpd when operating in DHCPv6 mode. There was also a bug in
dhcpd relating to the use of this function per its documentation, but the
bug in the library function prevented this from causing any harm. All
releases of dhcpd from ISC contain copies of this, and other, BIND
libraries in combinations that have been tested prior to release and are
known to not present issues like this. Some third-party packagers of ISC
software have modified the dhcpd source, BIND source, or version matchup in
ways that create the crash potential. Based on reports available to ISC,
the crash probability is large and no analysis has been done on how, or
even if, the probability can be manipulated by an attacker. Affects: Builds
of dhcpd versions prior to version 4.4.1 when using BIND versions 9.11.2 or
later, or BIND versions with specific bug fixes backported to them. ISC
does not have access to comprehensive version lists for all repackagings of
dhcpd that are vulnerable. In particular, builds from other vendors may
also be affected. Operators are advised to consult their vendor
mdeslaurissue in isc-dhcp was introduced by the following change in
bind in bionic+:
Ubuntu 12.04 ESM (Precise Pangolin):not-affected
Ubuntu 14.04 ESM (Trusty Tahr):not-affected
Ubuntu 16.04 LTS (Xenial Xerus):not-affected
Ubuntu 18.04 LTS (Bionic Beaver):released (4.3.5-3ubuntu7.1)
More Information

Updated: 2020-07-28 20:07:47 UTC (commit d26b6ca9f5b3adb89bb036ce73ae7dab894935ec)