{"api_version":"1","generated_at":"2026-08-07T01:05:42+00:00","cve":"CVE-2026-66843","urls":{"html":"https://cve.report/CVE-2026-66843","api":"https://cve.report/api/cve/CVE-2026-66843.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-66843","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-66843"},"summary":{"title":"html_sanitize_ex HTML5 scrubber keeps attacker-supplied `<object>` elements, allowing untrusted content embedding","description":"Inclusion of Functionality from Untrusted Control Sphere vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to load a document of their choosing into a trusted page via the data attribute of an <object> element in sanitized HTML. object is the one URI-bearing element in lib/html_sanitize_ex/scrubber/html5.ex never registered through allow_tag_with_uri_attributes/3, and its only guard is a prefix match on lowercase \"javascript:\", so mixed-case variants, data: URIs, protocol-relative URLs and same-origin paths all survive.\n\nThis is not unconditional cross-site scripting. 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A <code>javascript:</code> URL does not execute through <code>&lt;object data&gt;</code> in current browsers, <code>data:</code> documents load in an opaque origin, and host-origin script execution additionally requires the application to serve attacker-controlled content from a same-origin path.</p>\n<p>This issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.</p>"},{"base64":false,"type":"text/markdown","value":"Inclusion of Functionality from Untrusted Control Sphere vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to load a document of their choosing into a trusted page via the `data` attribute of an `<object>` element in sanitized HTML. `object` is the one URI-bearing element in `lib/html_sanitize_ex/scrubber/html5.ex` never registered through `allow_tag_with_uri_attributes/3`, and its only guard is a prefix match on lowercase `\"javascript:\"`, so mixed-case variants, `data:` URIs, protocol-relative URLs and same-origin paths all survive.\n\nThis is not unconditional cross-site scripting. 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