Medium 6.1Published Oct 2, 2026

CVE-2026-104477Showdown through 2.1.0 XSS via unescaped quote in href and src attributes

Updated under an hour ago (2026-10-19 09:10 UTC)

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It affects showdownjs showdown. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for showdownjs showdown

Exploited in the last 30 days

Showdown through 2.1.0 contains a cross-site scripting vulnerability in the makehtml link and image subparsers, which fail to escape double quotes in destination URLs placed into href and src attributes. Attackers can craft markdown links or images containing a double quote followed by onerror or onmouseover handlers to execute script when victims view rendered HTML.

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: Awaiting Analysis
Record last updated: Oct 5, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

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

References

https://github.com/showdownjs/showdown/commit/4fb992cd26631c108ec0410342630c80207ec7c6patch
https://github.com/showdownjs/showdownproduct
https://www.vulncheck.com/advisories/showdown-through-2.1.0-xss-via-unescaped-quote-in-href-and-src-attributesthird-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.