diff --git a/gbpui/column_filters.py b/gbpui/column_filters.py
index 8318f9e..b7c526a 100644
--- a/gbpui/column_filters.py
+++ b/gbpui/column_filters.py
@@ -14,6 +14,8 @@ import os
 
 from django.conf import settings
 from django.urls import reverse
+from django.utils.html import format_html
+from django.utils.html import format_html_join
 from django.utils.safestring import mark_safe
 
 from gbpui import client
@@ -29,12 +31,12 @@ def update_pruleset_attributes(request, prset):
     rules = prset.policy_rules
     url = "horizon:project:application_policy:policyruledetails"
     value = ["<ul>"]
-    li = lambda x: "<li><a href='" + \
-        reverse(url, kwargs={'policyrule_id': x.id}) + \
-        "'>" + x.name + "</a></li>"
     for rule in rules:
         r = client.policyrule_get(request, rule)
-        value.append(li(r))
+        li = format_html("<li><a href='{}'>{}</a></li>",
+                         reverse(url, kwargs={'policyrule_id': r.id}),
+                         r.name)
+        value.append(li)
     value.append("</ul>")
     value = "".join(value)
     setattr(prset, 'policy_rules', mark_safe(value))
@@ -47,10 +49,10 @@ def update_service_policy_attributes(policy):
     if len(np) > 0:
         tags = []
         for item in np:
-            dl = ["<dl class='dl-horizontal'>"]
-            dl.extend(["<dt>%s<dt><dd>%s</dd>" %
-                (k, v) for k, v in list(item.items())])
-            dl.append("</dl>")
+            dl = [mark_safe("<dl class='dl-horizontal'>")]
+            dl.extend(format_html_join('', "<dt>{}<dt><dd>{}</dd>",
+                ((k, v) for k, v in list(item.items()))))
+            dl.append(mark_safe("</dl>"))
             tags.append("".join(dl))
         params = mark_safe("".join(tags))
     setattr(policy, 'network_service_params', params)
@@ -64,16 +66,15 @@ def update_policy_target_attributes(request, pt):
     provided = [client.policy_rule_set_get(request, item) for item in provided]
     consumed = [client.policy_rule_set_get(request, item) for item in consumed]
     p = ["<ul>"]
-    li = lambda x: "<li><a href='" + \
-        reverse(url, kwargs={'policy_rule_set_id': x.id}) + \
-        "'>" + x.name + "</a></li>"
+    li = lambda url, item: (format_html("<li><a href='{}'>{}</a></li>",
+        reverse(url, kwargs={'policy_rule_set_id': item.id}), item.name))
     for item in provided:
-        p.append(li(item))
+        p.append(li(url, item))
     p.append("</ul>")
     p = "".join(p)
     c = ["<ul>"]
     for item in consumed:
-        c.append(li(item))
+        c.append(li(url, item))
     c.append("</ul>")
     c = "".join(c)
     consumed = [item.name for item in consumed]
@@ -83,15 +84,14 @@ def update_policy_target_attributes(request, pt):
     if hasattr(pt, 'l2_policy_id') and pt.l2_policy_id is not None:
         policy = client.l2policy_get(request, pt.l2_policy_id)
         u = reverse(l2url, kwargs={'l2policy_id': policy.id})
-        atag = mark_safe(
-            "<a href='" + u + "'>" + policy.name + "</a>")
+        atag = format_html("<a href='{}'>{}</a>", u, policy.name)
         setattr(pt, 'l2_policy_id', atag)
     if hasattr(pt, 'external_segments'):
         exturl = "horizon:project:network_policy:external_connectivity_details"
         value = ["<ul>"]
-        li = lambda x: "<li><a href='" + \
-            reverse(exturl, kwargs={'external_connectivity_id': x.id}) + \
-            "'>" + x.name + "</a></li>"
+        li = lambda x: format_html("<li><a href='{}'>{}</a></li>",
+            reverse(exturl, kwargs={'external_connectivity_id': x.id}),
+            x.name)
         for external_segment in pt.external_segments:
             ext_policy = client.get_externalconnectivity(request,
                 external_segment)
@@ -107,22 +107,22 @@ def update_policyrule_attributes(request, prule):
     classifier_id = prule.policy_classifier_id
     classifier = client.policyclassifier_get(request, classifier_id)
     u = reverse(url, kwargs={'policyclassifier_id': classifier.id})
-    tag = mark_safe("<a href='" + u + "'>" + classifier.name + "</a>")
+    tag = format_html("<a href='{}'>{}</a>", u, classifier.name)
     setattr(prule, 'policy_classifier_id', tag)
     actions = prule.policy_actions
     action_url = "horizon:project:application_policy:policyactiondetails"
-    ul = ["<ul>"]
+    ul = [mark_safe("<ul>")]
     for a in actions:
         action = client.policyaction_get(request, a)
         u = reverse(action_url, kwargs={'policyaction_id': a})
         if action.action_type == 'redirect':
             spec = client.get_servicechain_spec(request, action.action_value)
             spec_details = "%s:%s" % (spec.name, str(spec.id))
-            li = "<li><a href='%s'>%s</a></li>" % (u, spec_details)
+            li = format_html("<li><a href='%s'>%s</a></li>", u, spec_details)
         else:
-            li = "<li><a href='%s'>%s</a></li>" % (u, action.name)
+            li = format_html("<li><a href='%s'>%s</a></li>", u, action.name)
         ul.append(li)
-    ul.append("</ul>")
+    ul.append(mark_safe("</ul>"))
     ultag = "".join(ul)
     setattr(prule, 'policy_actions', mark_safe(ultag))
     return prule
@@ -292,17 +292,15 @@ def update_classifier_attributes(classifiers):
 def update_l3_policy_attributes(request, l3_policy):
     url = "horizon:project:network_policy:external_connectivity_details"
     if bool(l3_policy.external_segments):
-        value = ["<ul>"]
-        li = \
-            lambda x: "<li><a href='" + \
-            reverse(url, kwargs={'external_connectivity_id': x.id}) + \
-             "'>" + x.name + "</a>" + " : " + \
-            l3_policy.external_segments[x.id][0] + "</li>"
+        value = [mark_safe("<ul>")]
+        li = lambda x: format_html("<li><a href='{}'>{}</a> : {}</li>",
+            reverse(url, kwargs={'external_connectivity_id': x.id}),
+            x.name, l3_policy.external_segments[x.id][0])
         for ec in list(l3_policy.external_segments.keys()):
             external_connectivity = client.get_externalconnectivity(request,
                                                                     ec)
             value.append(li(external_connectivity))
-        value.append("</ul>")
+        value.append(mark_safe("</ul>"))
         tag = mark_safe("".join(value))
     else:
         tag = '-'
@@ -313,15 +311,13 @@ def update_l3_policy_attributes(request, l3_policy):
 def update_nat_pool_attributes(request, nat_pool):
     url = "horizon:project:network_policy:external_connectivity_details"
     id = nat_pool.external_segment_id
-    value = ["<ul>"]
-    li = \
-        lambda x: "<li><a href='" + \
-        reverse(url, kwargs={'external_connectivity_id': x.id}) + \
-        "'>" + x.name + "</a>" + "</li>"
+    value = [mark_safe("<ul>")]
+    li = lambda x: format_html("<li><a href='{}'>{}</a></li>",
+        reverse(url, kwargs={'external_connectivity_id': x.id}), x.name)
     external_connectivity = client.get_externalconnectivity(request,
                                                                 id)
     value.append(li(external_connectivity))
-    value.append("</ul>")
+    value.append(mark_safe("</ul>"))
     tag = mark_safe("".join(value))
     setattr(nat_pool, 'external_segment_id', tag)
     return nat_pool
diff --git a/gbpui/fields.py b/gbpui/fields.py
index 111feb3..51b3872 100644
--- a/gbpui/fields.py
+++ b/gbpui/fields.py
@@ -88,11 +88,11 @@ class DropdownEditWidget(TextInput):
     def render(self, name, value, attrs=None):
         text_html = super(DropdownEditWidget, self).render(
             name, value, attrs=attrs)
-        data_list = '<datalist id="list__%s">' % self._name
+        data_list = [format_html('<datalist id="list__{}">', self._name)]
         for item in self._list:
-            data_list += '<option value="%s">' % item
-        data_list += '</datalist>'
-        return mark_safe(text_html + data_list)
+            data_list.append(format_html('<option value="{}">', item))
+        data_list.append(mark_safe('</datalist>'))
+        return mark_safe(text_html + mark_safe("".join(data_list)))
 
 
 class TransferTableWidget(widgets.SelectMultiple):
@@ -134,7 +134,7 @@ class TransferTableWidget(widgets.SelectMultiple):
 
         open_tag = format_html('<d-table {}>', flatatt(final_attrs))
 
-        output = [open_tag, options, '</d-table>']
+        output = [open_tag, options, mark_safe('</d-table>')]
 
         return mark_safe('\n'.join(output))
 
diff --git a/gbpui/panels/application_policy/forms.py b/gbpui/panels/application_policy/forms.py
index 4722721..320a05c 100644
--- a/gbpui/panels/application_policy/forms.py
+++ b/gbpui/panels/application_policy/forms.py
@@ -167,7 +167,9 @@ class UpdatePolicyActionForm(BaseUpdateForm):
             self.fields['name'].initial = pa.name
             self.fields['description'].initial = pa.description
             self.fields['shared'].initial = pa.shared
-        except Exception:
+        except KeyError:
+            pass
+        except AttributeError:
             pass
 
     def handle(self, request, context):
diff --git a/gbpui/panels/policytargets/forms.py b/gbpui/panels/policytargets/forms.py
index 354fe89..24f4868 100644
--- a/gbpui/panels/policytargets/forms.py
+++ b/gbpui/panels/policytargets/forms.py
@@ -460,7 +460,9 @@ class AddConsumedPRSForm(forms.SelfHandlingForm):
             policy_rule_sets = [
                 (p.id, p.name) for p in items
                 if p.id not in consumedpolicy_rule_sets]
-        except Exception:
+        except AttributeError:
+            pass
+        except KeyError:
             pass
         self.fields['policy_rule_set'].choices = policy_rule_sets
 
@@ -508,7 +510,9 @@ class ExtAddConsumedPRSForm(forms.SelfHandlingForm):
             policy_rule_sets = [
                 (p.id, p.name) for p in items
                 if p.id not in consumedpolicy_rule_sets]
-        except Exception:
+        except AttributeError:
+            pass
+        except KeyError:
             pass
         self.fields['policy_rule_set'].choices = policy_rule_sets
 
@@ -557,7 +561,9 @@ class RemoveConsumedPRSForm(forms.SelfHandlingForm):
             policy_rule_sets = [(p.id, p.name)
                                 for p in items if p.id
                                 in consumedpolicy_rule_sets]
-        except Exception:
+        except AttributeError:
+            pass
+        except KeyError:
             pass
         self.fields['policy_rule_set'].choices = policy_rule_sets
 
@@ -605,7 +611,9 @@ class ExtRemoveConsumedPRSForm(forms.SelfHandlingForm):
             policy_rule_sets = [(p.id, p.name)
                                 for p in items if p.id
                                 in consumedpolicy_rule_sets]
-        except Exception:
+        except AttributeError:
+            pass
+        except KeyError:
             pass
         self.fields['policy_rule_set'].choices = policy_rule_sets
 
diff --git a/gbpui/panels/policytargets/views.py b/gbpui/panels/policytargets/views.py
index 0c6c83e..6b0b858 100644
--- a/gbpui/panels/policytargets/views.py
+++ b/gbpui/panels/policytargets/views.py
@@ -66,7 +66,9 @@ class PTGDetailsView(tabs.TabbedTableView):
             policy_target = client.policy_target_get(
                 self.request, context['policy_target_id'])
             context['policy_target'] = policy_target
-        except Exception:
+        except AttributeError:
+            pass
+        except KeyError:
             pass
         return context
 
@@ -83,7 +85,9 @@ class ExternalPTGDetailsView(tabs.TabbedTableView):
             ext_policy_target = client.ext_policy_target_get(
                 self.request, context['ext_policy_target_id'])
             context['policy_target'] = ext_policy_target
-        except Exception:
+        except AttributeError:
+            pass
+        except KeyError:
             pass
         return context
 
diff --git a/gbpui/panels/policytargets/workflows.py b/gbpui/panels/policytargets/workflows.py
index 8c866ac..b58cff8 100644
--- a/gbpui/panels/policytargets/workflows.py
+++ b/gbpui/panels/policytargets/workflows.py
@@ -592,7 +592,8 @@ class LaunchInstance(workflows.Workflow):
                             try:
                                 subnet = api.neutron.subnet_get(
                                     request, subnet_id)
-                            except Exception:
+                            except Exception as e:
+                                LOG.warning(str(e))
                                 continue
                             if IPAddress(fixed_ip) in \
                                     IPNetwork(subnet['cidr']):
diff --git a/tools/install_venv_common.py b/tools/install_venv_common.py
index e279159..51a912d 100644
--- a/tools/install_venv_common.py
+++ b/tools/install_venv_common.py
@@ -26,7 +26,7 @@ from __future__ import print_function
 
 import optparse
 import os
-import subprocess
+import subprocess  # nosec
 import sys
 
 
@@ -61,7 +61,7 @@ class InstallVenv(object):
         else:
             stdout = None
 
-        proc = subprocess.Popen(cmd, cwd=self.root, stdout=stdout)
+        proc = subprocess.Popen(cmd, cwd=self.root, stdout=stdout)  # nosec
         output = proc.communicate()[0]
         if check_exit_code and proc.returncode != 0:
             self.die('Command "%s" failed.\n%s', ' '.join(cmd), output)