CVE-2026-59711

showdown contains a cross-site scripting vulnerability in metadata title handling that allows attackers to inject arbitrary HTML and JavaScript. When completeHTMLDocument option is enabled, unescaped less-than and greater-than characters in markdown frontmatter metadata are inserted directly into HTML title tags, enabling attackers to break out of the title context and execute malicious scripts in the rendered page.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/showdownjs/showdown
https://github.com/showdownjs/showdown/issues/1047
https://www.vulncheck.com/advisories/showdown-cross-site-scripting-via-unescaped-metadata-title-in-completehtmldocument
https://github.com/showdownjs/showdown/issues/1047

Configurations

No configuration.

History

07 Jul 2026, 15:16

Type	Values Removed	Values Added
References	~~() https://github.com/showdownjs/showdown/issues/1047 -~~	() https://github.com/showdownjs/showdown/issues/1047 -

06 Jul 2026, 21:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-06 21:16

Updated : 2026-07-07 15:16

NVD link : CVE-2026-59711

Mitre link : CVE-2026-59711

CVE.ORG link : CVE-2026-59711

JSON object : View

Products Affected

No product.

CWE

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

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