CVE-2026-59710
Medium
Description
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.
SeverityMedium
CVSS6.1
Exploit probability—
Product
Showdown
PublishedJul 6, 2026
First seenJul 6, 2026
Weakness typeCWE-79Cross-site scripting (XSS)
How to fix
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| showdownnpm | v ≤ 2.1.0 | — |
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