The issue appears to be that JBoss EAP 6.4.21 does not parse the field-name in accordance to RFC7230[1] as it returns a 200 instead of a 400.
https://bugzilla.redhat.com/show_bug.cgi?id=1793970
Source: Mitre, NVD
Published: 2020-09-16
Updated: 2020-09-22
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N
Severity: Medium
Base Score: 5.3
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N