Tomcat returns 400 for a request containing an invalid Host header

Solution Verified - Updated -


  • We have some requests with an invalid host header, such as the scheme being included in it (http://localhost:8080). Such requests were accepted previously but now receive 400 responses after upgrading Tomcat.


  • JBoss Web Server (JWS) 5.x
  • Tomcat
    • 8.0.52+
    • 9.0.5+

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