HashiCorp Consul and Consul Enterprise include an HTTP API (introduced in 1.2.0) and DNS (introduced in 1.4.3) caching feature that was vulnerable to denial of service. Fixed in 1.6.6 and 1.7.4.
https://github.com/hashicorp/consul/pull/8023
https://github.com/hashicorp/consul/blob/v1.7.4/CHANGELOG.md
https://github.com/hashicorp/consul/blob/v1.6.6/CHANGELOG.md