Form data theft via retained form-association attributes
Published Aug 6, 2026 · Updated Aug 19, 2026
Open redirect in René Föhring html_sanitize_ex 0.3.1 through 1.4.4 and 1.5.0-rc.0 through 1.5.2 lets remote attackers capture form data. The HTML5 scrubber retains the form and formaction attributes on attacker-controlled input elements, letting an absolute cross-origin URL override an existing form's action. Exploitation requires sanitized output rendered to another user on a page with a predictable form id, and captures only data the victim submits.
Summary
What happened
Open redirect in René Föhring html_sanitize_ex 0.3.1 through 1.4.4 and 1.5.0-rc.0 through 1.5.2 lets remote attackers capture form data. The HTML5 scrubber retains the form and formaction attributes on attacker-controlled input elements, letting an absolute cross-origin URL override an existing form's action. Exploitation requires sanitized output rendered to another user on a page with a predictable form id, and captures only data the victim submits.
The record
- CVE
- CVE-2026-66370
- Published
- Aug 6, 2026
- Updated
- Aug 19, 2026
- Vendor
- René Föhring
- Product
- html_sanitize_ex
- Classifications
- CWE-601, CAPEC-154, T1056
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 6, 2026CVE publishedPublication date reported by the CVE source.
- Aug 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.3.1 <1.4.5
- Affected versionversion=1.5.0-rc.0 <1.5.3
- Affected versionversion=8976d64ea0b77d26093a94a43ec48a3978e8d028 <* changes=[{"at":"a1e804ed997e780ea71d14393cf2f701330553a6","status":"unaffected"},{"at":"21394e758cb0ffe12fb9953c30fdedc6016c8f9e","status":"unaffected"}]
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What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
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Technologies
Your stack
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Your stack
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