CVE-2026-66829
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 element in sanitized HTML. HtmlSanitizeEx.html5/1 keeps attacker-supplied 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.
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Affected products
2cpe:2.3:a:rrrene:htmlsanitizeex:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:rrrene:htmlsanitizeex:*:*:*:*:*:*:*:*range: >=0.3.1,<1.5.3
- (no CPE)range: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3
Patches
Vulnerability mechanics
References
5- cna.erlef.org/cves/CVE-2026-66829.htmlnvdPatchThird Party Advisory
- github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76fnvdPatch
- osv.dev/vulnerability/EEF-CVE-2026-66829nvdPatchThird Party Advisory
- github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcrnvdBroken Link
- github.com/rrrene/html_sanitize_ex/commit/29454dc99513fd9b5b6429ab7b6695ad09889227nvd
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