Medium 6.1Published Jul 6, 2026

CVE-2026-59710showdown - Stored XSS via Unescaped Table Header ID Attribute Injection

Updated under an hour ago (Oct 26, 2026, 10:30 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for showdown

Exploited in the last 30 days

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.

CVSS: 6.1 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness (CWE): CWE-79
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: VulnCheck
NVD analysis: Deferred
Record last updated: Jul 7, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

showdown showdown showdown:showdown (from the name)	through 2.1.0	CNA record

References

https://github.com/showdownjs/showdown/issues/1046issue-tracking
https://github.com/showdownjs/showdownproduct
https://github.com/showdownjs/showdown/commit/e5cab1e9a5dcea2bb3cbf888863fa7e65ab37edfpatch
https://www.vulncheck.com/advisories/showdown-stored-xss-via-unescaped-table-header-id-attribute-injectionthird-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.