ByteOS Network

NVD Vulnerability Details :

CVE-2026-59711

Deferred

Source-disclosure@vulncheck.com

Published At-06 Jul, 2026 | 21:16

Updated At-07 Jul, 2026 | 15:16

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.

Date Added	Due Date	Vulnerability Name	Required Action
	N/A

Metrics

Type	Version	Base score	Base severity	Vector
Secondary	4.0	5.3	MEDIUM	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Secondary	3.1	6.1	MEDIUM	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
			N/A

Type: Secondary

Version: 4.0

Base score: 5.3

Base severity: MEDIUM

Vector:

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Type: Secondary

Version: 3.1

Base score: 6.1

Base severity: MEDIUM

Vector:

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

Type: N/A

Version:

Base score:

Base severity: N/A

Vector:

Weaknesses

CWE ID	Type	Source
CWE-79	Secondary	disclosure@vulncheck.com

CWE ID: CWE-79

Type: Secondary

Source: disclosure@vulncheck.com

References

Hyperlink	Source	Resource
https://github.com/showdownjs/showdown	disclosure@vulncheck.com	N/A
https://github.com/showdownjs/showdown/issues/1047	disclosure@vulncheck.com	N/A
https://www.vulncheck.com/advisories/showdown-cross-site-scripting-via-unescaped-metadata-title-in-completehtmldocument	disclosure@vulncheck.com	N/A
https://github.com/showdownjs/showdown/issues/1047	134c704f-9b21-4f2e-91b3-4a467353bcc0	N/A