Vulnerability Description
URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the attacker's choosing via a <meta http-equiv="refresh"> element in sanitized HTML. HtmlSanitizeEx.html5/1 keeps attacker-supplied <meta> elements in its output. A meta element acts on the whole document rather than on the fragment it was embedded in, so it can also declare document-wide directives such as Content-Security-Policy. This is not cross-site scripting. Browsers do not navigate a meta refresh to a javascript: URL, so the uppercase JAVASCRIPT: filter bypass yields no script execution and none was demonstrated. This issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.
Related Weaknesses (CWE)
References
- https://cna.erlef.org/cves/CVE-2026-66829.html
- https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af
- https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xp
- https://osv.dev/vulnerability/EEF-CVE-2026-66829
FAQ
What is CVE-2026-66829?
CVE-2026-66829 is a documented vulnerability. URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to force visitors of a page to navigate to a site of the att...
How severe is CVE-2026-66829?
CVSS scoring is not yet available for CVE-2026-66829. Check NVD for updates.
Is there a patch for CVE-2026-66829?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.