Sending a maliciously crafted message to the kea-ctrl-agent, kea-dhcp-ddns, kea-dhcp4, or kea-dhcp6 daemons over any configured API socket or HA listener can cause the receiving daemon to exit with a stack overflow error. This issue affects Kea versions 2.6.0 through 2.6.4 and 3.0.0 through 3.0.2.

Last updated 8 June 2026

To trigger the issue, three configuration parameters must have specific settings: "hostname-char-set" must be left at the default setting, which is "[^A-Za-z0-9.-]"; "hostname-char-replacement" must be empty (the default); and "ddns-qualifying-suffix" must NOT be empty (the default is empty). DDNS updates do not need to be enabled for this issue to manifest. A client that sends certain option content would then cause kea-dhcp4 to exit unexpectedly. This issue affects Kea versions 3.0.1 through 3.0.1 and 3.1.1 through 3.1.2.

To trigger the issue, three configuration parameters must have specific settings: "hostname-char-set" must be left at the default setting, which is "[^A-Za-z0-9.-]"; "hostname-char-replacement" must be empty (the default); and "ddns-qualifying-suffix" must NOT be empty (the default is empty). DDNS updates do not need to be enabled for this issue to manifest. A client that sends certain option content would then cause kea-dhcp4 to exit unexpectedly. This issue affects Kea versions 3.0.1 through 3.0.1 and 3.1.1 through 3.1.2.

In some cases, Kea log files or lease files may be world-readable.

Kea configuration and API directives can be used to overwrite arbitrary files, subject to permissions granted to Kea. Many common configurations run Kea as root, leave the API entry points unsecured by default, and/or place the control sockets in insecure paths. This issue affects Kea versions 2.4.0 through 2.4.1, 2.6.0 through 2.6.2, and 2.7.0 through 2.7.8.

Kea configuration and API directives can be used to load a malicious hook library. Many common configurations run Kea as root, leave the API entry points unsecured by default, and/or place the control sockets in insecure paths. This issue affects Kea versions 2.4.0 through 2.4.1, 2.6.0 through 2.6.2, and 2.7.0 through 2.7.8.

A missing check on incoming client requests can be exploited to cause a situation where the Kea server's lease storage contains leases which are rejected as invalid when the server tries to load leases from storage on restart. If the number of such leases exceeds a hard-coded limit in the Kea code, a server trying to restart will conclude that there is a problem with its lease store and give up. Versions affected: 1.4.0 to 1.5.0, 1.6.0-beta1, and 1.6.0-beta2

A packet containing a malformed DUID can cause the Kea DHCPv6 server process (kea-dhcp6) to exit due to an assertion failure. Versions affected: 1.4.0 to 1.5.0, 1.6.0-beta1, and 1.6.0-beta2.