CVE-2026-104477

MEDIUM 6.1

Showdown through 2.1.0 XSS via unescaped quote in href and src attributes

CVSS Score

6.1

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-79
Vendor	showdownjs
Product	showdown
Published	Oct 2, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Affected Versions

showdownjs / showdown

0 ≤ 2.1.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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

Credits

Muhammad Sobirov