{"cve":"CVE-2026-66843","nvd":{"published":"2026-08-06T16:16:49.627","modified":"2026-10-24T16:10:00.153","status":"Modified","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. A javascript: URL does not execute through <object data> 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 1.4.5 and from 1.5.0-rc.0 before 1.5.3.","cvss_v4":{"vector":"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","score":2.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","score":6.1},"cwes":["CWE-829"],"references":["https://cna.erlef.org/cves/CVE-2026-66843.html","https://github.com/rrrene/html_sanitize_ex/commit/bec27fec4de99e40c68c4285a610e09e791a3eaf","https://github.com/rrrene/html_sanitize_ex/commit/ce038aa1af5a960d50f8eb5d368cc57bb2b9a9f0","https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-xmm9-jc22-rcgj","https://osv.dev/vulnerability/EEF-CVE-2026-66843"],"products":["rrrene:htmlsanitizeex"],"source":"nvd","synced_at":"2026-10-24T16:53:34.184483516+00:00"},"epss":{"cve":"CVE-2026-66843","score":0.00512,"percentile":0.43369,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}