{"id":"GHSA-wq5h-f9p5-q7fx","summary":"Improper validation of URLs ('Cross-site Scripting') in Wagtail rich text fields","details":"### Impact\nWhen 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.\n\n### Patches\nPatched 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).\n\n### Workarounds\nFor 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:\n\n```python\nfrom draftjs_exporter.dom import DOM\nfrom wagtail.admin.rich_text.converters.html_to_contentstate import ExternalLinkElementHandler, PageLinkElementHandler\nfrom wagtail.core import hooks\nfrom wagtail.core.whitelist import check_url\n\n\ndef link_entity(props):\n    id_ = props.get('id')\n    link_props = {}\n\n    if id_ is not None:\n        link_props['linktype'] = 'page'\n        link_props['id'] = id_\n    else:\n        link_props['href'] = check_url(props.get('url'))\n\n    return DOM.create_element('a', link_props, props['children'])\n\n\n@hooks.register('register_rich_text_features', order=1)\ndef register_link(features):\n    features.register_converter_rule('contentstate', 'link', {\n        'from_database_format': {\n            'a[href]': ExternalLinkElementHandler('LINK'),\n            'a[linktype=\"page\"]': PageLinkElementHandler('LINK'),\n        },\n        'to_database_format': {\n            'entity_decorators': {'LINK': link_entity}\n        }\n    })\n```\n\n### Acknowledgements\nMany thanks to Kevin Breen for reporting this issue.\n\n### For more information\nIf you have any questions or comments about this advisory:\n\n* Visit Wagtail's [support channels](https://docs.wagtail.io/en/stable/support.html)\n* Email us at security@wagtail.io (if you wish to send encrypted email, the public key ID is `0x6ba1e1a86e0f8ce8`)","aliases":["CVE-2021-29434","PYSEC-2021-114"],"modified":"2026-05-07T05:01:33.556863090Z","published":"2021-04-20T14:02:30Z","database_specific":{"nvd_published_at":"2021-04-19T19:15:00Z","cwe_ids":["CWE-79"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2021-04-19T18:46:26Z"},"references":[{"type":"WEB","url":"https://github.com/wagtail/wagtail/security/advisories/GHSA-wq5h-f9p5-q7fx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-29434"},{"type":"WEB","url":"https://github.com/wagtail/wagtail/commit/5c7a60977cba478f6a35390ba98cffc2bd41c8a4"},{"type":"WEB","url":"https://github.com/wagtail/wagtail/commit/915f6ed2bd7d53154103cc4424a0f18695cdad6c"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/wagtail/PYSEC-2021-114.yaml"},{"type":"PACKAGE","url":"https://github.com/wagtail/wagtail"},{"type":"WEB","url":"https://github.com/wagtail/wagtail/compare/v2.11.6...v2.11.7"},{"type":"WEB","url":"https://pypi.org/project/wagtail"}],"affected":[{"package":{"name":"wagtail","ecosystem":"PyPI","purl":"pkg:pypi/wagtail"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.11.7"}]}],"versions":["0.1","0.2","0.3","0.3.1","0.4","0.4.1","0.5","0.6","0.7","0.8","0.8.1","0.8.10","0.8.2","0.8.3","0.8.4","0.8.5","0.8.6","0.8.7","0.8.8","0.8.9","1.0","1.0b1","1.0b2","1.0rc1","1.0rc2","1.1","1.10","1.10.1","1.10rc1","1.11","1.11.1","1.11rc1","1.12","1.12.1","1.12.2","1.12.3","1.12.4","1.12.5","1.12.6","1.12rc1","1.13","1.13.1","1.13.2","1.13.3","1.13.4","1.13rc1","1.1rc1","1.2","1.2rc1","1.3","1.3.1","1.3rc1","1.4","1.4.1","1.4.2","1.4.3","1.4.4","1.4.5","1.4.6","1.4rc1","1.5","1.5.1","1.5.2","1.5.3","1.5rc1","1.6","1.6.1","1.6.2","1.6.3","1.6rc1","1.7","1.7rc1","1.8","1.8.1","1.8.2","1.8rc1","1.9","1.9.1","1.9rc1","2.0","2.0.1","2.0.2","2.0b1","2.0rc1","2.1","2.1.1","2.1.2","2.1.3","2.10","2.10.1","2.10.2","2.10rc1","2.10rc2","2.11","2.11.1","2.11.2","2.11.3","2.11.4","2.11.5","2.11.6","2.11rc1","2.1rc1","2.1rc2","2.2","2.2.1","2.2.2","2.2rc1","2.2rc2","2.3","2.3rc1","2.3rc2","2.4","2.4rc1","2.5","2.5.1","2.5.2","2.5rc1","2.6","2.6.1","2.6.2","2.6.3","2.6rc1","2.7","2.7.1","2.7.2","2.7.3","2.7.4","2.7rc1","2.7rc2","2.8","2.8.1","2.8.2","2.8rc1","2.9","2.9.1","2.9.2","2.9.3","2.9rc1"],"database_specific":{"last_known_affected_version_range":"\u003c= 2.11.6","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/04/GHSA-wq5h-f9p5-q7fx/GHSA-wq5h-f9p5-q7fx.json"}},{"package":{"name":"wagtail","ecosystem":"PyPI","purl":"pkg:pypi/wagtail"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.12"},{"fixed":"2.12.4"}]}],"versions":["2.12","2.12.1","2.12.2","2.12.3"],"database_specific":{"last_known_affected_version_range":"\u003c= 2.12.3","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/04/GHSA-wq5h-f9p5-q7fx/GHSA-wq5h-f9p5-q7fx.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"}]}