CVE-2026-59710
showdown - Stored XSS via Unescaped Table Header ID Attribute Injection
CVSS Score
6.1
EPSS Score
0.2%
EPSS Percentile
10th
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.
| CWE | CWE-79 |
| Vendor | showdown |
| Product | showdown |
| Published | Jul 6, 2026 |
| Last Updated | Jul 7, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Affected Versions
showdown / showdown
0 ≤ 2.1.0
References
github.com: https://github.com/showdownjs/showdown/issues/1046 github.com: https://github.com/showdownjs/showdown github.com: https://github.com/showdownjs/showdown/commit/e5cab1e9a5dcea2bb3cbf888863fa7e65ab37edf vulncheck.com: https://www.vulncheck.com/advisories/showdown-stored-xss-via-unescaped-table-header-id-attribute-injection
Credits
🔍 Scott Moore - VulnCheck