Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

CVE-2026-54889

Gravedad CVSS v4.0:
MEDIA
Tipo:
CWE-79 Neutralización incorrecta de la entrada durante la generación de la página web (Cross-site Scripting)
Fecha de publicación:
29/06/2026
Última modificación:
30/06/2026

Descripción

*** Pendiente de traducción *** Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in leandrocp mdex allows cross-site scripting via unsanitized URL schemes in Quill Delta output.<br /> <br /> &amp;#39;Elixir.MDEx&amp;#39;:to_delta/2 converts Markdown into a Quill Delta. &amp;#39;Elixir.MDEx.DeltaConverter&amp;#39;:default_convert_node/3 in lib/mdex/delta_converter.ex copies the URL of a link, wikilink, or image node directly from the parsed Markdown into the Delta "link" or "image" attribute without applying a scheme allowlist or any normalization.<br /> <br /> An attacker who controls the Markdown text can supply a javascript: URL (for example [click](javascript:alert(document.cookie))) that survives verbatim into the Delta attribute. When the Delta is rendered to HTML by a downstream renderer (such as quill-delta-to-html or the Quill client), the attribute becomes an or , and the javascript: scheme executes in the browser of anyone who views the rendered content. The link and wikilink cases are the strongest vectors because javascript: in an href executes on click; the image case is lower impact because javascript: in generally does not execute in modern browsers.<br /> <br /> This issue affects mdex: from 0.8.3 before 0.13.2.