Wagtail Cross-site Scripting

Wagtail is an open source content management system built on Django. A cross-site scripting vulnerability exists in versions 2.13-2.13.1, versions 2.12-2.12.4, and versions prior to 2.11.8. When the `{% include_block %}` template tag is used to output the value of a plain-text StreamField block (`CharBlock`, `TextBlock` or a similar user-defined block derived from `FieldBlock`), and that block does not specify a template for rendering, the tag output is not properly escaped as HTML. This could allow users to insert arbitrary HTML or scripting. This vulnerability is only exploitable by users with the ability to author StreamField content (i.e. users with 'editor' access to the Wagtail admin). Patched versions have been released as Wagtail 2.11.8 (for the LTS 2.11 branch), Wagtail 2.12.5, and Wagtail 2.13.2 (for the current 2.13 branch). As a workaround, site implementors who are unable to upgrade to a current supported version should audit their use of `{% include_block %}` to ensure it is not used to output `CharBlock` / `TextBlock` values with no associated template. Note that this only applies where `{% include_block %}` is used directly on that block (uses of `include_block` on a block _containing_ a CharBlock / TextBlock, such as a StructBlock, are unaffected). In these cases, the tag can be replaced with Django's `{{ ... }}` syntax - e.g. `{% include_block my_title_block %}` becomes `{{ my_title_block }}`. (2021-06-17, CVE-2021-32681)

Wagtail is a Django content management system. In affected versions of Wagtail, when saving the contents of a rich text field in the admin interface, Wagtail does not apply server-side checks to ensure that link URLs use a valid protocol. A malicious user with access to the admin interface could thus craft a POST request to publish content with `javascript:` URLs containing arbitrary code. The vulnerability is not exploitable by an ordinary site visitor without access to the Wagtail admin. See referenced GitHub advisory for additional details, including a workaround. Patched versions have been released as Wagtail 2.11.7 (for the LTS 2.11 branch) and Wagtail 2.12.4 (for the current 2.12 branch). (2021-04-19, CVE-2021-29434)

In Wagtail before versions 2.7.4 and 2.9.3, when a form page type is made available to Wagtail editors through the `wagtail.contrib.forms` app, and the page template is built using Django's standard form rendering helpers such as form.as_p, any HTML tags used within a form field's help text will be rendered unescaped in the page. Allowing HTML within help text is an intentional design decision by Django; however, as a matter of policy Wagtail does not allow editors to insert arbitrary HTML by default, as this could potentially be used to carry out cross-site scripting attacks, including privilege escalation. This functionality should therefore not have been made available to editor-level users. The vulnerability is not exploitable by an ordinary site visitor without access to the Wagtail admin. Patched versions have been released as Wagtail 2.7.4 (for the LTS 2.7 branch) and Wagtail 2.9.3 (for the current 2.9 branch). In these versions, help text will be escaped to prevent the inclusion of HTML tags. Site owners who wish to re-enable the use of HTML within help text (and are willing to accept the risk of this being exploited by editors) may set WAGTAILFORMS_HELP_TEXT_ALLOW_HTML = True in their configuration settings. Site owners who are unable to upgrade to the new versions can secure their form page templates by rendering forms field-by-field as per Django's documentation, but omitting the |safe filter when outputting the help text. (2020-07-20, CVE-2020-15118)

In Wagtail before versions 2.8.1 and 2.7.2, a cross-site scripting (XSS) vulnerability exists on the page revision comparison view within the Wagtail admin interface. A user with a limited-permission editor account for the Wagtail admin could potentially craft a page revision history 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. Patched versions have been released as Wagtail 2.7.2 (for the LTS 2.7 branch) and Wagtail 2.8.1 (for the current 2.8 branch). (2020-04-14, CVE-2020-11001)

Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.

The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:

https://server.com/confirmation?message=Transaction+Complete

what results in:

<span>Confirmation: Transaction Complete</span>

In that case the message can be modified to become a valid Javascript code, e.g.:

https://server.com/confirmation?message=<script>dangerous javascript code here</script>

and it will be executed locally by the user's browser with full access to the user's personal application/browser data:

<span>Confirmation: <script>dangerous javascript code here</script></span>