sep@nlnetlabs.nl reports:
NLnet Labs Unbound up to and including version 1.24.0 is vulnerable
to possible domain hijack attacks. Promiscuous NS RRSets that
complement positive DNS replies in the authority section can be
used to trick resolvers to update their delegation information for
the zone. Usually these RRSets are used to update the resolver's
knowledge of the zone's name servers. A malicious actor can
exploit the possible poisonous effect by injecting NS RRSets (and
possibly their respective address records) in a reply. This could
be done for example by trying to spoof a packet or fragmentation
attacks. Unbound would then proceed to update the NS RRSet data
it already has since the new data has enough trust for it, i.e.,
in-zone data for the delegation point. Unbound 1.24.1 includes a
fix that scrubs unsolicited NS RRSets (and their respective address
records) from replies mitigating the possible poison effect.