PT-2026-56013 · Showdown · Showdown

Vc-Smoore · Published 2026-07-06 · Updated 2026-07-06 · CVE-2026-59711

Mitre

CVSS v3.1

6.1

Medium

Base vector

AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

showdown contains a cross-site scripting vulnerability in metadata title handling that allows attackers to inject arbitrary HTML and JavaScript. When completeHTMLDocument option is enabled, unescaped less-than and greater-than characters in markdown frontmatter metadata are inserted directly into HTML title tags, enabling attackers to break out of the title context and execute malicious scripts in the rendered page.

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-59711

Affected Products

Showdown

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-59711 · Security Note
• https://github.com/showdownjs/showdown/issues/1047 · Note
• https://github.com/showdownjs/showdown · Note
• https://vulncheck.com/advisories/showdown-cross-site-scripting-via-unescaped-metadata-title-in-completehtmldocument · Note