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Wagtail vulnerable to stored Cross-site Scripting attack via ModelAdmin views

Moderate severity GitHub Reviewed Published Apr 3, 2023 in wagtail/wagtail • Updated Apr 3, 2023

Package

pip wagtail (pip)

Affected versions

>= 1.5, < 4.1.4
>= 4.2, < 4.2.2

Patched versions

4.1.4
4.2.2

Description

Impact

A stored cross-site scripting (XSS) vulnerability exists on ModelAdmin views within the Wagtail admin interface. A user with a limited-permission editor account for the Wagtail admin could potentially craft pages and documents that, when viewed by a user with higher privileges, could perform actions with that user's credentials. The vulnerability is not exploitable by an ordinary site visitor without access to the Wagtail admin, and only affects sites with ModelAdmin enabled.

  • For page, the vulnerability is in the "Choose a parent page" ModelAdmin view (ChooseParentView), available when managing pages via ModelAdmin.
  • For documents, the vulnerability is in the ModelAdmin Inspect view (InspectView) when displaying document fields.

Patches

Patched versions have been released as Wagtail 4.1.4 (for the LTS 4.1 branch) and Wagtail 4.2.2 (for the current 4.2 branch).

Workarounds

Site owners who are unable to upgrade to the new versions can disable or override the corresponding functionality.

ChooseParentView

For ChooseParentView:

  • Disable ModelAdmin for all page models.
  • Or provide a custom view via choose_parent_view_class, with the custom view overriding the get_form method.

One of those steps need to be applied for every ModelAdmin class hooked into Wagtail where the model is a Wagtail Page or sub-class. Here is an example of implementing the custom ChooseParentView with patched HTML escaping:

from django import forms
from django.utils.translation import gettext as _
from wagtail.contrib.modeladmin.views import ChooseParentView
from wagtail.contrib.modeladmin.forms import ParentChooserForm


class PatchedPageChoiceField(forms.ModelChoiceField):
    """PageChoiceField with plain-text breadcrumbs to patch stored XSS."""
    def label_from_instance(self, obj):
        bits = []
        for ancestor in (
            obj.get_ancestors(inclusive=True).exclude(depth=1).specific(defer=True)
        ):
            bits.append(ancestor.get_admin_display_title())
        return ' | '.join(bits)


class PatchedParentChooserForm(ParentChooserForm):
    """ParentChooserForm with custom parent_page to patch stored XSS."""
    parent_page = PatchedPageChoiceField(
        label=_("Parent page"),
        required=True,
        empty_label=None,
        queryset=Page.objects.none(),
        widget=forms.RadioSelect(),
    )


class PatchedChooseParentView(ChooseParentView):
    """ChooseParentView with custom get_form patch stored XSS."""
    def get_form(self, request):
        parents = self.permission_helper.get_valid_parent_pages(request.user)
        return PatchedParentChooserForm(parents, request.POST or None)

InspectView

For InspectView:

One of those steps need to be applied for every ModelAdmin class hooked into Wagtail where inspect_view_enabled=True. Here is an example of implementing the custom InspectView with patched HTML escaping:

from django.template.defaultfilters import filesizeformat
from django.utils.html import format_html
from wagtail.contrib.modeladmin.views import InspectView


class PatchedInspectView(InspectView):
    """InspectView with override to patch stored XSS vulnerability."""
    def get_document_field_display(self, field_name, field):
        """Render a link to a document"""
        document = getattr(self.instance, field_name)
        if document:
            return format_html(
                '<a href="{}">{} <span class="meta">({}, {})</span></a>',
                document.url,
                document.title,
                document.file_extension.upper(),
                filesizeformat(document.file.size),
            )
        return self.model_admin.get_empty_value_display(field_name)

References

@gasman gasman published to wagtail/wagtail Apr 3, 2023
Published by the National Vulnerability Database Apr 3, 2023
Published to the GitHub Advisory Database Apr 3, 2023
Reviewed Apr 3, 2023
Last updated Apr 3, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
High
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H

EPSS score

0.101%
(43rd percentile)

Weaknesses

CVE ID

CVE-2023-28836

GHSA ID

GHSA-5286-f2rf-35c2

Source code

Credits

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