CVE-2026-104477

Medium

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.

SeverityMedium

CVSS6.1

Exploit probability—

Product

Showdown

PublishedOct 3, 2026

First seenOct 3, 2026

Weakness typeCWE-79Cross-site scripting (XSS)

How to fix

Patches

github.com/showdownjs/showdown/commit/4fb992cd26631c108ec0410342630c80207ec7c6

Affected products

Product	Affected versions	Fixed in
showdownjs showdown	v ≤ 2.1.0	—

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