The good news is that the bug is fixed in master, the upcoming 2.4 release. So, while we were able to reproduce the issue, we are not going to release 2.3.10 for now. This issue is simply not critical enough on its own to warrant delaying 2.4 further. It might not seem like it, but even a bugfix release usually takes most of a week of work.
I can't give a definite date for 2.4, but we are already freezing the milestone. Until it is released, there are multiple ways to work around the issue. The easiest one is disabling
enable_jsvm in your config, as we have found it's the cause of the leak. That's only possible if you don't need to use JS plugins, of course.
Otherwise, you can always restart the gateway if the memory use increases too much. Hopefully that won't be necessary too often.
If you have any more questions or issues, feel free to get in touch. Thanks!