CVE-2021-42697: Uncontrolled Recursion in Akka HTTP

The vulnerability stems from uncontrolled recursion during HTTP header comment parsing. The advisory explicitly mentions stack exhaustion from deeply nested comments, and the patch introduced 'max-comment-parsing-depth' configuration. The workaround suggests disabling modeled header parsing, implicating HeaderParser's comment handling. While exact code isn't available, Akka's architecture places header parsing logic in HeaderParser.scala, with recursive comment parsing being a common pattern in parser implementations. The CWE-674 classification further supports the recursion control failure hypothesis.