Several vulnerabilities have been discovered in the ISC DHCP client,
relay and server.
It was discovered that the DHCP server does not correctly perform
option reference counting when configured with "allow leasequery;".
A remote attacker can take advantage of this flaw to cause a denial
of service (daemon crash).
It was discovered that the DHCP server is prone to a memory leak
flaw when handling contents of option 81 (fqdn) data received in
a DHCP packet. A remote attacker can take advantage of this flaw
to cause DHCP servers to consume resources, resulting in denial
For the stable distribution (bullseye), these problems have been fixed in version 4.4.1-2.3+deb11u1.
We recommend that you upgrade your isc-dhcp packages.