CVE-2026-66829
Received
Received - Intake
Open Redirect in html_sanitize_ex via HTML5 Scrubber
Vulnerability report for CVE-2026-66829, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-08-06
Last updated on: 2026-08-06
Assigner: EEF
Description
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.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| rrrene | html_sanitize_ex | From 0.3.1 (inc) to 1.5.3 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-601 | The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect. |
