Improper validation of URLs ('Cross-site Scripting') in Wagtail rich text fields
Impact
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.
Patches
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).
Workarounds
For sites that cannot easily upgrade to a current supported version, the vulnerability can be patched by adding the following code to a wagtail_hooks.py module in any installed app:
from draftjs_exporter.dom import DOM
from wagtail.admin.rich_text.converters.html_to_contentstate import ExternalLinkElementHandler, PageLinkElementHandler
from wagtail.core import hooks
from wagtail.core.whitelist import check_url
def link_entity(props):
id_ = props.get('id')
link_props = {}
if id_ is not None:
link_props['linktype'] = 'page'
link_props['id'] = id_
else:
link_props['href'] = check_url(props.get('url'))
return DOM.create_element('a', link_props, props['children'])
@hooks.register('register_rich_text_features', order=1)
def register_link(features):
features.register_converter_rule('contentstate', 'link', {
'from_database_format': {
'a[href]': ExternalLinkElementHandler('LINK'),
'a[linktype="page"]': PageLinkElementHandler('LINK'),
},
'to_database_format': {
'entity_decorators': {'LINK': link_entity}
}
})Acknowledgements
Many thanks to Kevin Breen for reporting this issue.
For more information
If you have any questions or comments about this advisory:
- Visit Wagtail's support channels
- Email us at security@wagtail.io (if you wish to send encrypted email, the public key ID is
0x6ba1e1a86e0f8ce8)
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | wagtail | < 2.11.7, >= 2.12, < 2.12.4 | 2.11.7, 2.12.4 |
References
- https://github.com/wagtail/wagtail/security/advisories/GHSA-wq5h-f9p5-q7fx
- https://pypi.org/project/wagtail/
- https://nvd.nist.gov/vuln/detail/CVE-2021-29434
- https://github.com/wagtail/wagtail/commit/5c7a60977cba478f6a35390ba98cffc2bd41c8a4
- https://github.com/wagtail/wagtail/commit/915f6ed2bd7d53154103cc4424a0f18695cdad6c
- https://github.com/pypa/advisory-database/tree/main/vulns/wagtail/PYSEC-2021-114.yaml
- https://github.com/wagtail/wagtail
- https://github.com/wagtail/wagtail/compare/v2.11.6...v2.11.7
- https://pypi.org/project/wagtail
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N- Weakness (CWE)
CWE-79- Platform
- Python (PyPI)
- Package
wagtail- Disclosed
- 19.04.2021
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2021-114 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-wq5h-f9p5-q7fx - CC BY 4.0
Vulnerability history: wagtail
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 30
- First → latest
- 04.2020 08.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 5
- Medium 22
- Low 3
Disclosures per year
- 2020: 3
- 2021: 2
- 2022: 1
- 2023: 3
- 2024: 3
- 2025: 0
- 2026: 18
-
Improper validation of URLs ('Cross-site Scripting') in Wagtail rich text fields this entry
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