@nuxtjs/mdc: the URL sanitizer misses SVG xlink:href and data:text/html, allowing XSS from untrusted markdown at the default configuration

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-63671
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-16 15:17:40 UTC
Updated2026-09-18 18:17:10 UTC
DescriptionMDC is a tool to take regular Markdown and write documents interacting deeply with a Vue component. Prior to 0.22.1, @nuxtjs/mdc uses parseMarkdown with allowDangerousHtml enabled by default and relies on validateProps, validateProp, and unsafeLinkPrefix to remove executable URLs from untrusted Markdown. validateProp checks only attributes named href or src, allowing an SVG xlink:href value represented as xLinkHref to retain a javascript: URL that executes in the page origin when selected. The data:text/html denylist entries are also compared against url.protocol, which is only data:, so an iframe src containing data:text/html survives sanitization and executes in an opaque origin when loaded. Plain href javascript: URLs, srcdoc, object, script, and base elements are already blocked, making these two paths specific sibling gaps in the sanitizer. This issue is fixed in version 0.22.1.

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from [email protected]

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

EPSS: 0.003840000 probability, percentile 0.323650000 (date 2026-09-19)

Problem Types: CWE-79 | CWE-184 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | CWE-184 CWE-184: Incomplete List of Disallowed Inputs

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
3.1CNADECLARED8.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Nuxt-content Mdc affected < 0.22.1 Not specified

References

ReferenceSourceLinkTags
github.com/nuxt-content/mdc/pull/491 [email protected] github.com
github.com/nuxt-content/mdc/security/advisories/GHSA-mxm6-v9r6-r94c 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/nuxt-content/mdc/commit/61d636c2983f021288e4fc5c4006733b38cf0d53 [email protected] github.com
github.com/nuxt-content/mdc/releases/tag/v0.22.1 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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