We faced the same problem. Afters hours and hours (days in fact) of research, we tried upgrade undertow lib.

We are under wildfly 24 (jdk 1.8.0_192), which uses undertow-core-2.2.8.Final. We solved the problem after upgrading it to undertow-core-2.2.37.Final ! (only on the front side).

Hope this could help...

Mickael.