CVE-2026-59710: Showdown

Medium severity, CVSS 6.1. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Showdown Showdown: up to and including 2.1.0

Published 2026-07-06. Last modified 2026-07-07.