CVE-2026-54260

Wagtail: Denial of service via unbounded filter specs in the image preview

from django.core.exceptions import PermissionDenied
from django.http import HttpResponseBadRequest
from django.shortcuts import get_object_or_404
from django.urls import path
from wagtail.admin import urls as wagtailadmin_urls
from wagtail.images.exceptions import InvalidFilterSpecError
from wagtail.images.permissions import permission_policy
from wagtail.images.views import preview


def patched_preview(request, image_id, filter_spec):
    image = get_object_or_404(get_image_model(), id=image_id)

    if not permission_policy.user_has_permission_for_instance(request.user, "change", image):
        raise PermissionDenied

    try:
        filter_obj = Filter(spec=filter_spec)
    except InvalidFilterSpecError:
        return HttpResponseBadRequest("Invalid filter spec", content_type="text/plain")

    allowed = {"original", "width", "height", "min", "max", "fill"}
    if any(operation.method not in allowed for operation in filter_obj.operations):
        return HttpResponseBadRequest("Invalid filter spec", content_type="text/plain")

    return preview(request, image_id, filter_spec)


urlpatterns = [
    # Example where the CMS admin is at /admin/.
    # Add this before the Wagtail admin URLs registration, with the same sub-path.
    path("admin/images/<int:image_id>/preview/<str:filter_spec>/", patched_preview)
    path("admin/", include(wagtailadmin_urls)),
]

An authenticated admin user can trigger expensive rendition processing with purposefully crafted filter specs resulting in potentially service degradation.

The vulnerability is not exploitable by an ordinary site visitor without access to the Wagtail admin.

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

CVE-2026-54260 has a CVSS score of 4.3 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (7.0.8, 7.3.3, 7.4.2); upgrading removes the vulnerable code path.

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Patched versions have been released as Wagtail 7.0.8, 7.3.3, 7.4.2.

1. What is CVE-2026-54260? CVE-2026-54260 is a medium-severity uncontrolled resource consumption vulnerability in wagtail (pip), affecting versions < 7.0.8. It is fixed in 7.0.8, 7.3.3, 7.4.2. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
2. How severe is CVE-2026-54260? CVE-2026-54260 has a CVSS score of 4.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of wagtail are affected by CVE-2026-54260? wagtail (pip) versions < 7.0.8 is affected.
4. Is there a fix for CVE-2026-54260? Yes. CVE-2026-54260 is fixed in 7.0.8, 7.3.3, 7.4.2. Upgrade to this version or later.
5. Is CVE-2026-54260 exploitable, and should I be worried? Whether CVE-2026-54260 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-54260 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-54260?
   • Upgrade wagtail to 7.0.8 or later
   • Upgrade wagtail to 7.3.3 or later
   • Upgrade wagtail to 7.4.2 or later

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