cPanel can ship with 5.8.8, 5.10 or 5.16 at '/usr/bin/perl/' depending on the server OS and tech choice. The newest cPanel also comes with Perl 5.22 at '/usr/local/cpanel/3rdparty/bin/perl'

My testbed runs Activestate Perl 5.16.3
This forum's host is running 5.8.8. Plus I can change the shebang and access Perl 5.14.4 at '/usr/local/cpanel/3rdparty/bin/perl'

YaBBForum is running Perl 5.12.4

I know some things have been deprecated between 5.16 and 5.22 so I'll check to see if 5.22 supports some of the Modules I need for my testbed so I can see what warnings it throws.

1462647464|1462647464|84.251.212.53|Tapahtui virhe! Subroutine main::find_latest_data redefined at Sources/BoardIndex.pm line 776.||||RJL|
1462647548|1462647548|54.221.104.60|Tapahtui virhe! Use of uninitialized value $template_print_post in concatenation (.) or string at Sources/Display.pm line 1438.||1368612703|haku||
1462647624|1462647624|40.77.167.12|Tapahtui virhe! Use of uninitialized value in string eq at ./Sources/RSS.pm line 341.|RSSrecent||||
1462648040|1462648039|157.55.39.73|Tapahtui virhe! Use of uninitialized value $template_print_post in concatenation (.) or string at Sources/Display.pm line 1438.||1368612703|haku||
1462648191|1462648191|188.143.232.70|Tapahtui virhe! Use of uninitialized value in concatenation (.) or string at ./Templates/srhs/Register.template line 288.|register||||
1462648195|1462648194|188.143.232.70|Tapahtui virhe! Use of uninitialized value in concatenation (.) or string at ./Sources/Search.pm line 74.|search||||

1462650296|1462650296|85.76.131.129|Tapahtui virhe! Value of <HANDLE> construct can be "0"; test with defined() at ./Sources/Memberlist.pm line 297.|ml|||vesa.k|

1462652613|1462652613|91.233.116.228|Selvitt�m�t�n virhe :<br />The 'epoch' parameter ("Ei tiedossa") to DateTime::from_epoch did not pass regex check at /usr/local/lib64/perl5/DateTime.pm line 488      DateTime::from_epoch(undef, 'epoch', 'Ei tiedossa') called at Sources/DateTime.pm line 54      main::toffs('Ei tiedossa', undef) called at Sources/DateTime.pm line 177      main::timeformat('Ei tiedossa') called at Sources/BoardIndex.pm line 457      main::BoardIndex() called at YaBB.pl line 226      main::yymain() called at YaBB.pl line 171      eval {...} called at YaBB.pl line 171||||TOH|

1462653210|1462653209|151.80.31.175|Tapahtui virhe! Use of /g modifier is meaningless in split at Sources/MediaCenter.pm line 135.||1420742338|muut_radiolaitteet||

So long as c-Panel ships with Perl 5.08, that's our oldest supported Perl. I know YaBB 2.52 through 2.6+ work on Perl 5.18 but there may be a deprecation problem with RSS.pm with Perl 5.2+ (Luckily the problem appears to be in section that can be safely removed as RSS.pm will never call it.)

The problems with older versions of YaBB is mostly deprecated code, very old html and very old javascript.