showdown allows stored cross-site scripting through table header ID injection
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | showdown | <= 2.1.0 | no fix |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-59710
- https://github.com/showdownjs/showdown/issues/1046
- https://github.com/showdownjs/showdown/commit/e5cab1e9a5dcea2bb3cbf888863fa7e65ab37edf
- https://github.com/showdownjs/showdown
- https://www.vulncheck.com/advisories/showdown-stored-xss-via-unescaped-table-header-id-attribute-injection
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
showdown- Disclosed
- 07.07.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-22g5-r2x5-97cx - CC BY 4.0
Vulnerability history: showdown
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 09.2020 07.2026
- Without a fix
- 3
- Exploited in attacks
- 0
Severity breakdown
- Medium 3
- Low 1
Disclosures per year
- 2020: 1
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 1
- 2025: 0
- 2026: 2
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showdown allows stored cross-site scripting through table header ID injection this entry
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