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CVE-2026-66370

html_sanitize_ex HTML5 scrubber keeps attacker-supplied form-association attributes, allowing form hijacking

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.4.5, 1.5.3
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • html_sanitize_ex

    From 0.3.1 · fixed in 1.4.5; From 1.5.0-rc.0 · fixed in 1.5.3

  • rrrene/html_sanitize_ex

    Version range not reported

References 5

GitHub · rrrene/html_sanitize_ex

cna.erlef.org

osv.dev