Prevent HTML injection in email preview (Z#23241741)

src/pretix/base/services/placeholders.py

@@ -801,11 +801,10 @@ def get_available_placeholders(event, base_parameters, rich=False):
     return params
 
 
-def get_sample_context(event, context_parameters, rich=True):
+def prepare_sample_context_for_preview(placeholder_to_sample):
     context_dict = {}
     lbl = _('This value will be replaced based on dynamic parameters.')
-    for k, v in get_available_placeholders(event, context_parameters, rich=rich).items():
-        sample = v.render_sample(event)
+    for k, sample in placeholder_to_sample.items():
         if isinstance(sample, PlainHtmlAlternativeString):
             context_dict[k] = PlainHtmlAlternativeString(
                 '<{el} class="placeholder" title="{title}">{plain}</{el}>'.format(
@@ -830,3 +829,12 @@ def get_sample_context(event, context_parameters, rich=True):
                 escape(sample)
             ))
     return context_dict
+
+
+def get_sample_context(event, context_parameters, rich=True):
+    return prepare_sample_context_for_preview(
+        {
+            k: v.render_sample(event)
+            for k, v in get_available_placeholders(event, context_parameters, rich=rich).items()
+        }
+    )

src/pretix/control/views/organizer.py

@@ -108,6 +108,7 @@ from pretix.base.services.export import (
     init_organizer_exporters, multiexport, scheduled_organizer_export,
 )
 from pretix.base.services.mail import mail, prefix_subject
+from pretix.base.services.placeholders import prepare_sample_context_for_preview
 from pretix.base.templatetags.rich_text import markdown_compile_email
 from pretix.base.views.tasks import AsyncAction
 from pretix.control.forms.exports import ScheduledOrganizerExportForm
@@ -345,16 +346,11 @@ class MailSettingsPreview(OrganizerPermissionRequiredMixin, View):
 
     # get all supported placeholders with dummy values
     def placeholders(self, item):
-        ctx = {}
-        for p, s in MailSettingsForm(obj=self.request.organizer)._get_sample_context(
-                MailSettingsForm.base_context[item]).items():
-            if s.strip().startswith('*'):
-                ctx[p] = s
-            else:
-                ctx[p] = '<span class="placeholder" title="{}">{}</span>'.format(
-                    _('This value will be replaced based on dynamic parameters.'),
-                    s
-                )
+        ctx = prepare_sample_context_for_preview(
+            MailSettingsForm(obj=self.request.organizer)._get_sample_context(
+                MailSettingsForm.base_context[item]
+            )
+        )
         return self.SafeDict(ctx)
 
     def post(self, request, *args, **kwargs):