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.
'Elixir.MDEx':to_delta/2 converts Markdown into a Quill Delta. 'Elixir.MDEx.DeltaConverter':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.
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 <a href> or <img src>, 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 <img src> generally does not execute in modern browsers.
This issue affects mdex: from 0.8.3 before 0.13.2.
CVSS
No CVSS.
References
Configurations
No configuration.
History
29 Jun 2026, 21:16
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://github.com/leandrocp/mdex/security/advisories/GHSA-4383-7xfp-gpph - |
29 Jun 2026, 20:17
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-06-29 20:17
Updated : 2026-06-30 14:14
NVD link : CVE-2026-54889
Mitre link : CVE-2026-54889
CVE.ORG link : CVE-2026-54889
JSON object : View
Products Affected
No product.
CWE
CWE-79
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')