SoftEther third party source code review
There have been numerous discussions regarding the inclusion of SoftEther into pfSense. Way back in 2014 when this was brought up @stephenw10 mentioned that
It needs some serious code review by people I trust before I could trust it.
Since then there's been several third party code reviews conducted by Max Planck Institute for Molecular Genetics and Mr. Guido Vranken in late 2017.