CVE-2026-59710
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.
- Score
- CVSS 3.1 6.1 Medium
- Status
- Deferred - disclosure@vulncheck.com
- Published
- 2026-07-06
- Last modified
- 2026-07-07
- Weaknesses
- CWE-79
Affected products
References
- https://github.com/showdownjs/showdown
- https://github.com/showdownjs/showdown/commit/e5cab1e9a5dcea2bb3cbf888863fa7e65ab37edf
- https://github.com/showdownjs/showdown/issues/1046
- https://www.vulncheck.com/advisories/showdown-stored-xss-via-unescaped-table-header-id-attribute-injection
