CVE-2026-59710 Details
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.
A stored cross-site scripting vulnerability exists in Showdown versions through 2.1.0. The issue arises in the 'parseHeaders' function within 'src/subParsers/makehtml/tables.js', where the table header ID attributes are not properly escaped. This flaw allows attackers to inject arbitrary HTML and script-executing SVG elements by using double-quote characters in markdown table headers. The vulnerability is triggered when untrusted markdown is rendered with the default GitHub flavor, which has table header IDs enabled.
Users can update to Showdown version 3.0.0 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 6, 2026CISA-ADP
Assessed Jul 7, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/showdownjs/showdown/issues/1046 | CISA-ADP | ExploitIssue TrackingTechnical DescriptionVendor |
| https://github.com/showdownjs/showdown | [email protected] | ProductSource CodeVendor |
| https://github.com/showdownjs/showdown/commit/e5cab1e9a5dcea2bb3cbf888863fa7e65ab37edf | [email protected] | Source CodeVendor |
| https://github.com/showdownjs/showdown/issues/1046 | [email protected] | ExploitIssue TrackingTechnical DescriptionVendor |
| https://www.vulncheck.com/advisories/showdown-stored-xss-via-unescaped-table-header-id-attribute-injection | [email protected] | AdvisoryRemedy |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| showdownjs showdown | <= 2.1.0 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 7, 2026 | CVE Modified | CISA-ADP |
| Jul 6, 2026 | New CVE Received | [email protected] |