If a server hosts a zone containing a "KEY" Resource Record, or a resolver DNSSEC-validates a "KEY" Resource Record from a DNSSEC-signed domain in cache, a client can exhaust resolver CPU resources by sending a stream of SIG(0) signed requests. This issue affects BIND 9 versions 9.0.0 through 9.11.37, 9.16.0 through 9.16.50, 9.18.0 through 9.18.27, 9.19.0 through 9.19.24, 9.9.3-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.49-S1, and 9.18.11-S1 through 9.18.27-S1. A flaw was found in the bind9 package, where if a DNS server hosts a zone containing a "KEY" resource record or a DNS resolver utilizes the DNSSEC validate feature to validate a "KEY" resource record, a malicious client could exhaust the CPU resourced from the resolver by sending a stream of SIG(0) signed requests. This issue can lead to a denial of service.
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