Comment 4 for bug 1869971

As Jason mentioned, equivalent functionality has existed in Koha for years; I am not aware of particular security issues in practice, although this bug report is quite correct that the potential exists for a naive or malicious local admin to put in undesirable script tags.

It is my opinion that a reversion is overkill and that Evergreen admins can manage the risk via proper training of their local admins and taking care about to whom they assign UPDATE_ORG_UNIT_SETTING.opac.patron.custom_css.

I have no objection to adding a config.tt2 flag and adjusting the wording of the library setting to warn against dangerous values . This can definitely be accomplished before general release (and I am willing to commit to doing the work); I am also willing to see if HTML::Defang or similar approaches can be readily applied to sanitize the values. For that matter, tossing Template Toolkit replace() filters in base.tt2 to zap < and > should help ameliorate the issue.

However, allowing local admins more direct and responsive control for tweaking their catalogs is a valuable feature that I would hate to see get lost.