CVE-2026-59710

MEDIUM

showdown - Stored XSS via Unescaped Table Header ID Attribute Injection

Title source: cna

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.

References (4)

Core 4

Core References

Issue Tracking issue-tracking

Pull Request

https://github.com/showdownjs/showdown/issues/1046

Product product

Product

https://github.com/showdownjs/showdown

Patch patch

https://github.com/showdownjs/showdown/commit/e5cab1e9a5dcea2bb3cbf888863fa7e65ab37edf

View Patch ZIP pw:eip

Third Party Advisory third-party-advisory

https://www.vulncheck.com/advisories/showdown-stored-xss-via-unescaped-table-header-id-attribute-injection

Scores

CVSS v3 6.1

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Details

CWE

CWE-79

Status published

Products (1)

showdown/showdown < 2.1.0

Published Jul 06, 2026

Tracked Since Jul 07, 2026