The Syracom Secure Login (2FA) plugin for Jira, Confluence, and Bitbucket through 3.1.4.5 allows remote attackers to easily brute-force the 2FA PIN via the plugins/servlet/twofactor/public/pinvalidation endpoint. The last 30 and the next 30 tokens are valid.
The product does not properly limit the number or frequency of interactions that it has with an actor, such as the number of incoming requests.