showdownjs/showdown · Security
showdown allows stored cross-site scripting through table header ID injection
- GHSA ID
- GHSA-22g5-r2x5-97cx
- CVE ID
- CVE-2026-59710
- Severity
- medium
- Published
- Updated
- CVSS
- 6.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- CVSS v3
- 6.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- CVSS v4
- 5.3 · 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
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.
CWEs
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
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 ↗
- https://github.com/advisories/GHSA-22g5-r2x5-97cx ↗