Akka HTTP 10.1.x and 10.2.x before 10.2.7 can encounter stack exhaustion while parsing HTTP headers, which allows a remote attacker to conduct a Denial of Service attack by sending a User-Agent header with deeply nested comments.
packetstormsecurity.com/files/167018/Akka-HTTP-10.1.14-Denial-Of-Service.html
akka.io/blog
akka.io/blog/news/2021/11/02/akka-http-10.2.7-released
akka.io/blog/news/2021/11/22/akka-http-10.1.15-released
doc.akka.io/docs/akka-http/current/security/2021-CVE-2021-42697-stack-overflow-parsing-user-agent.html
github.com/akka/akka-http
nvd.nist.gov/vuln/detail/CVE-2021-42697