PT-2026-56029 · Showdown · Showdown

Vc-Smoore · Published 2026-07-06 · Updated 2026-07-06 · CVE-2026-59710

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 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.

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-59710

Affected Products

Showdown

References · 5

• https://github.com/showdownjs/showdown/commit/e5cab1e9a5dcea2bb3cbf888863fa7e65ab37edf · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-59710 · Security Note
• https://github.com/showdownjs/showdown/issues/1046 · Note
• https://github.com/showdownjs/showdown · Note
• https://vulncheck.com/advisories/showdown-stored-xss-via-unescaped-table-header-id-attribute-injection · Note