CVE-2026-59710CWE-79

showdown - Stored XSS via Unescaped Table Header ID Attribute Injection

Medium · published July 6, 2026

CVSS v4.0
5.3
EPSS
0%
Percentile
26.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
5.3 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
EPSS
0.00338 · 26.0th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-07-06T21:15Z
EPSS history
Timeline
  • 06 JUL 21:15Z
    showdown - Stored XSS via Unescaped Table Header ID Attribute Injection
    cvelistv5