Probably caused by https://issues.apache.org/jira/browse/CXF-8840 .
Started to notice that when updating from 3.5.x to 3.6.0 that our servers started getting OOM. Noticed from the resulting logs that a lot of threads were active that were in the format
when reverted to 3.5.6 then it did not occur anymore.
Tried to use VirtualVM when debugging it and saw when the thread was started, it never died, basically meaning that it ran indefinitely. OOM happened when there were about over 1000 of these threads.