A programming error in the nxdomain-redirect feature can cause an assertion failure in query.c if the alternate namespace used by nxdomain-redirect is a descendant of a zone that is served locally. The most likely scenario where this might occur is if the server, in addition to performing NXDOMAIN redirection for recursive clients, is also serving a local copy of the root zone or using mirroring to provide the root zone, although other configurations are also possible. Versions affected: BIND 9.12.0-> 9.12.4, 9.14.0. Also affects all releases in the 9.13 development branch.