Severity: moderate
CVSS 4.0: 6.3 (medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Affected versions:
- Apache Wicket (org.apache.wicket:wicket-core) 8.0.0 through 8.19.0
- Apache Wicket (org.apache.wicket:wicket-core) 9.0.0 through 9.24.0
- Apache Wicket (org.apache.wicket:wicket-core) 10.0.0 through 10.11.0
Description:
Incorrect behavior order in Apache Wicket: a file path is validated before the
framework appends the attributes that complete it.
org.apache.wicket.request.resource.PackageResource asks the configured package
resource guard about a path built from the scope class' package and the file
name in the request URL, and then hands that same path to the resource stream
locator together with a style, a variation and a locale. Those three attributes
are decoded from the name of the first query parameter and never appear in the
string the guard was given.
org.apache.wicket.core.util.resource.locator.ResourceNameIterator appends them
to that path, each preceded by an underscore, in the order variation, style,
locale, before the file extension, so the file that is opened is not the file
the guard approved.
org.apache.wicket.markup.html.PackageResourceGuard decides whether an HTML file
is a component's markup template by looking for a class file of the same name
beside it, stripping one underscore-delimited suffix at a time as it goes. HTML
is on the default allow list, so that check is the only thing separating a
static HTML file, which may be served, from a markup template, which may not.
Asked about the name of a template, the guard refuses it correctly. Asked about
a shorter name for which no class exists, it accepts, and a style supplied in
the URL then completes that name into the markup template of a component class,
which is written to the response.
An application is affected if the simple name of any of its component classes
contains an underscore and no shorter part of that name is itself a class, such
as Report_v2 or Wizard_Step1; an application with no such class name is not
affected. No unusual deployment, packaging or configuration is required, and
running in deployment rather than development mode does not prevent it. Java
naming conventions discourage underscores in class names and no module Wicket
ships has one, so no framework markup is exposed; what an application exposes
this way is its own. A component whose class name has no underscore is not
reachable, and neither is its localized or styled markup, because the guard
finds the class file under the base name and refuses the request. The
attributes cannot change the file extension and cannot leave the component's
package, so nothing beyond HTML files in that package is reachable. Access is
read-only, and what is disclosed is developer-authored template content:
component structure, developer comments, markup that is rendered only under
some conditions, inline script, and the endpoints a template names. No user
data, credential or session material is reachable this way. An attacker has to
name a class in the target package and the component itself, and Wicket writes
fully qualified class names into the URL of every package resource it renders.
This issue affects Apache Wicket: from 8.0.0 through 8.19.0, from 9.0.0 through
9.24.0, from 10.0.0 through 10.11.0. Users of Apache Wicket 7.x or older, which
are no longer supported, should upgrade to a supported version. Users are
recommended to upgrade to version 8.20.0, 9.25.0 or 10.12.0, which fix the
issue.
Credit:
Emond Papegaaij (finder)
References:
https://wicket.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-84177
