{"id":"CVE-2026-66843","summary":"html_sanitize_ex HTML5 scrubber keeps attacker-supplied `\u003cobject\u003e` elements, allowing untrusted content embedding","details":"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 \u003cobject\u003e 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. A javascript: URL does not execute through \u003cobject data\u003e in current browsers, data: 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.\n\nThis issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.","aliases":["EEF-CVE-2026-66843","GHSA-xmm9-jc22-rcgj"],"modified":"2026-08-09T03:30:50.531078422Z","published":"2026-08-06T14:48:20.513Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66843.json","unresolved_ranges":[{"extracted_events":[{"introduced":"8976d64ea0b77d26093a94a43ec48a3978e8d028"},{"fixed":"bec27fec4de99e40c68c4285a610e09e791a3eaf"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"EEF","cwe_ids":["CWE-829"]},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-66843.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-66843"},{"type":"WEB","url":"https://repo.hex.pm"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66843.json"},{"type":"ADVISORY","url":"https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-xmm9-jc22-rcgj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-66843"},{"type":"FIX","url":"https://github.com/rrrene/html_sanitize_ex/commit/bec27fec4de99e40c68c4285a610e09e791a3eaf"},{"type":"PACKAGE","url":"https://github.com/rrrene/html_sanitize_ex"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/rrrene/html_sanitize_ex","events":[{"introduced":"088f92b18a4a3911a862b527d5eb3713f9abac24"},{"fixed":"f25255c82a3c6034a57d934718e10c982d29fa31"},{"fixed":"bec27fec4de99e40c68c4285a610e09e791a3eaf"}],"database_specific":{"extracted_events":[{"introduced":"0.3.1"},{"fixed":"1.5.3"}],"source":["DESCRIPTION","REFERENCES"]}}],"versions":["v1.5.2","v1.5.1","v1.5.0","v1.5.0-rc.0","v1.4.4","v1.4.3","v1.4.2","v1.4.1","v1.2.0","v1.0.1","v1.0.0","v0.3.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-66843.json"}}],"schema_version":"1.8.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"}]}