CVE-2026-104477

MEDIUMCVSS 6.1

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.

Timeline

Published:October 3rd, 2026 12:16 AM

Last modified:October 5th, 2026 9:16 PM

CVSS Scoring

CVSS v3: 6.1 (MEDIUM)

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Weaknesses (CWE)

CWE-79

References & Reports

Advisories, patches, and third-party reports

https://github.com/showdownjs/showdown
https://github.com/showdownjs/showdown/commit/4fb992cd26631c108ec0410342630c80207ec7c6
https://www.vulncheck.com/advisories/showdown-through-2.1.0-xss-via-unescaped-quote-in-href-and-src-attributes

Source: NIST NVD · Data may lag official sources by up to one minute