showdown allows stored cross-site scripting through table header ID injection

showdown Updated 08 Aug 2026

Summary

07/07/2026

Disclosed on

CVE-2026-59710

CVE

No i

Fix available

Moderate

Severity

6.1

CVSS Score

CVE-2026-59710: showdown allows stored cross-site scripting through table header ID injection. Affects showdown versions < 2.1.0. No fix is published. How to fix ↓

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showdown contains a stored cross-site scripting vulnerability in the parseHeaders function of src/subParsers/makehtml/tables.js that fails to properly escape table header ID attributes. Attackers can inject arbitrary HTML and script-executing SVG elements through double-quote characters in markdown table headers, achieving stored XSS when untrusted markdown is rendered with the default github flavor configuration.