CVE-2026-66829
html_sanitize_ex HTML5 scrubber keeps attacker-supplied meta refresh, allowing forced cross-origin redirection
- State
- Published
- Severity
- 2.3 Low
- Published
- Aug 6, 2026
- Updated
- Aug 19, 2026
- Reserved
- Aug 6, 2026
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 1.4.5 and from 1.5.0-rc.0 before 1.5.3.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 2.3 Low | 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 | EEF |
Weaknesses
- CWE-601 URL Redirection to Untrusted Site ('Open Redirect')
Affected Products
| Product | Versions |
|---|---|
html_sanitize_exrrrene |
|
html_sanitize_exrrrene |
|
References
- https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-2c6f-3j54-xpcrvendor-advisoryrelated
- https://cna.erlef.org/cves/CVE-2026-66829.htmlrelated
- https://osv.dev/vulnerability/EEF-CVE-2026-66829related
- https://github.com/rrrene/html_sanitize_ex/commit/9f7e38be51edc38f132dfe994f37af5cf5e0e76fpatch
- https://github.com/rrrene/html_sanitize_ex/commit/29454dc99513fd9b5b6429ab7b6695ad09889227patch
Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.