Threats Tagged 'cve-2026-66843'

CVE-2026-66843 is a low-severity vulnerability in the html_sanitize_ex library by rrrene. It involves the inclusion of functionality from an untrusted control sphere via the data attribute of an <object> element in sanitized HTML. This allows a remote attacker to load arbitrary documents into a trusted page. However, this is not unconditional cross-site scripting, as javascript: URLs do not execute through <object data> in current browsers, and data: documents load in an opaque origin. Exploitation requires the application to serve attacker-controlled content from a same-origin path.

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. This 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. 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.