CVE-2026-66370
6.1 · MEDIUMOverview
CVE-2026-66370 is a medium-severity vulnerability affecting rrrene htmlsanitizeex. It was published on August 6, 2026 and has a CVSS 3.1 base score of 6.1 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 6.1, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the form and formaction attributes on an <input> element in sanitized HTML. HTML's form attribute associates an input with any form on the page by its id even when the input sits outside that form, and formaction on a submit control overrides the owning form's action. Neither attribute receives a scheme check, so an absolute cross-origin URL survives sanitizing.
No script executes. The scrubber allows neither form nor button, so the attacker cannot introduce a form of their own and the rendering page must already contain a form carrying an id.
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.
Remediation
Check the references section for vendor advisories and patches from rrrene. Update htmlsanitizeex to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| rrrene | htmlsanitizeex | >= 0.3.1, < 1.5.3 | Affected |
References
Frequently Asked Questions
What is CVE-2026-66370?
CVE-2026-66370 is a medium-severity vulnerability affecting rrrene htmlsanitizeex. It was published on August 6, 2026 and has a CVSS 3.1 base score of 6.1 (MEDIUM).
How severe is CVE-2026-66370?
This vulnerability has a CVSS 3.1 base score of 6.1, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-66370?
Check the references section for vendor advisories and patches from rrrene. Update htmlsanitizeex to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-66370?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-66370 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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