CVE-2026-104477: Showdownjs Showdown

Medium severity, CVSS 6.1. EPSS: 0.2% chance of exploitation in the next 30 days.

Showdown through 2.1.0 contains a cross-site scripting vulnerability in the makehtml link and image subparsers, which fail to escape double quotes in destination URLs placed into href and src attributes. Attackers can craft markdown links or images containing a double quote followed by onerror or onmouseover handlers to execute script when victims view rendered HTML.

Affected products

• Showdownjs Showdown: up to and including 2.1.0

Published 2026-10-03. Last modified 2026-10-06.