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.
- CVSS 4.0
- 2.3
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N - CVSS 3.1
- 6.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - EPSS
- 0.6% chance of exploitation in the next 30 days; higher than 46% of CVEs (scores of 2026-10-25)
- CWE
- CWE-601
- Published
- Modified
- Record from
- the NVD, synced
Affected
- rrrene:htmlsanitizeex
References
- https://cna.erlef.org/cves/CVE-2026-66829.html
- https://github.com/rrrene/html_sanitize_ex/commit/29454dc99513fd9b5b6429ab7b6695ad09889227
- https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76f
- https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcr
- https://osv.dev/vulnerability/EEF-CVE-2026-66829