HashiCorp Vault and Vault Enterprise allowed the renewal of nearly-expired token leases and dynamic secret leases (specifically, those within 1 second of their maximum TTL), which caused them to be incorrectly treated as non-expiring during subsequent use. Fixed in 1.5.9, 1.6.5, and 1.7.2.
https://www.hashicorp.com/blog/category/vault/