DescriptionThere 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 documentation.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium
Debian Bugs896122

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
isc-dhcp (PTS)stretch4.3.5-3+deb9u1vulnerable
stretch (security)4.3.5-3+deb9u2vulnerable
bullseye, sid4.4.1-2.3fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs


[stretch] - isc-dhcp <ignored> (Issue triggerable only when build against bind >= 9.11.3)
[jessie] - isc-dhcp <ignored> (Issue triggerable only when build against bind >= 9.11.3)
Issue is caused by
isc-dhcp builds against system bind library, and commit for upstream
issue 4829 is first introduced in 9.11.3+dfsg-1. The underlying issue
is only uncovered when build gainst versions >= 9.11.3.

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