CVE-2026-104477

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.

  • Published Oct 3, 2026
  • CVSS 5.3 medium
  • 0.2% chance of exploitation in the next 30 days (EPSS)
  • A fix is available

Affected software

CVE-2026-104477 at the National Vulnerability Database