CVE-2026-66370

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.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://cna.erlef.org/cves/CVE-2026-66370.html	Patch Third Party Advisory
https://github.com/rrrene/html_sanitize_ex/commit/21394e758cb0ffe12fb9953c30fdedc6016c8f9e
https://github.com/rrrene/html_sanitize_ex/commit/a1e804ed997e780ea71d14393cf2f701330553a6	Patch
https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-w3f9-jjhw-wwvq	Broken Link
https://osv.dev/vulnerability/EEF-CVE-2026-66370	Patch Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:rrrene:htmlsanitizeex:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-08-06 16:16

Updated : 2026-08-19 12:18

NVD link : CVE-2026-66370

Mitre link : CVE-2026-66370

CVE.ORG link : CVE-2026-66370

JSON object : View

Products Affected

rrrene

htmlsanitizeex

CWE

CWE-601

URL Redirection to Untrusted Site ('Open Redirect')

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