CVE-2026-66829

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 1.4.5 and from 1.5.0-rc.0 before 1.5.3.

• CWE-601

• https://cna.erlef.org/cves/CVE-2026-66829.htmlPatch, Third Party Advisory
• https://github.com/rrrene/html_sanitize_ex/commit/29454dc99513fd9b5b6429ab7b6695ad09889227
• https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76fPatch
• https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcrBroken Link
• https://osv.dev/vulnerability/EEF-CVE-2026-66829Patch, Third Party Advisory

Published

Aug 6, 2026

Last Modified

Aug 19, 2026

Status

Modified

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