A flaw was found in the way unbound before 1.6.8 validated wildcard-synthesized NSEC records. An improperly validated wildcard NSEC record could be used to prove the non-existence (NXDOMAIN answer) of an existing wildcard record, or trick unbound into accepting a NODATA proof.
[
{
"product": "unbound",
"vendor": "NLnet Labs",
"versions": [
{
"status": "affected",
"version": "before 1.6.8"
}
]
}
]