Vulnerability · Published Oct 2, 2026 · Assigned by VulnCheck

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

Medium 6.1

In plain English

A medium-severity cross-site scripting in showdown from showdownjs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 8% of all known vulnerabilities).

Severity (CVSS 3.1)6.1Medium

Exploit odds (30 days)0.2%top 91.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
showdownjs	showdown	0 – through 2.1.0

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

Patch Commit patch
https://github.com/showdownjs/showdown product
VulnCheck Advisory: Showdown through 2.1.0 XSS via unescaped quote in href and src attributes third-party-advisory