A flaw was reported in WildFly 12.0.0.CR1 web server is vulnerable to the injection of arbitrary HTTP Header due to insufficient sanitisation and validation of user UTF-8 encoded input before it is used as part of an HTTP header value.

Although there is a protection against CRLF injection by detecting the presence of a NewLine character (0x0a), it can be bypassed using characters encoded in UTF-8 as the page will try to convert them back to the original Unicode form and extract the last byte.

An information leak vulnerability was found in Undertow. If all headers are not written out in the first write() call then the code that handles flushing the buffer will always write out the full contents of the writevBuffer buffer, which may contain data from previous requests.