RFC 4592, "The Role of Wildcards in the Domain Name System", July 2006Source of RFC: dnsext (int)
Errata ID: 5119
Reported By: Karst Koymans
Date Reported: 2017-09-21
Section 4.7 says:
4.7. NSEC RRSet at a Wildcard Domain Name Wildcard domain names in DNSSEC signed zones will have an NSEC RRSet. Synthesis of these records will only occur when the query exactly matches the record. Synthesized NSEC RRs will not be harmful as they will never be used in negative caching or to generate a negative response [RFC2308].
It should say:
4.7. NSEC RRSet at a Wildcard Domain Name Wildcard domain names in DNSSEC signed zones will have an NSEC RRSet. NSEC RRSets must not be synthesized from this wildcard NSEC.
Synthesizing these records would destroy the semantics of the NSEC chain and could be very harmful if implementations would cache them and use them for "Aggressive Use of DNSSEC-Validated Cache" (RFC 8198).