Astro: XSS via unescaped code for unsupported languages in @astrojs/prism

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-126365
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-13 00:20:12 UTC
Updated2026-11-13 00:20:12 UTC
DescriptionAstro is a web framework for content-driven websites. Prior to @astrojs/prism 4.1.2, and from @astrojs/markdoc 0.3.0 until 2.1.2, runHighlighterWithAstro() returned code unchanged when Prism had no grammar for the requested language, and callers inserted that result as raw HTML. A code block labeled with an unsupported language could therefore render embedded HTML and script instead of displaying it as text. The Prism component was affected when applications supplied untrusted code with an unsupported or attacker-controlled lang, and the @astrojs/markdoc prism() extension was affected for less-trusted content authors even when Markdoc's ordinary HTML rendering was disabled. This issue is fixed in @astrojs/prism 4.1.2 and @astrojs/markdoc 2.1.2.

Risk And Classification

Primary CVSS: v3.1 5.4 MEDIUM from [email protected]

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

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.1CNADECLARED5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Withastro Astro affected < 7.4.3 Not specified
CNA @astrojs Prism affected < 4.1.2 Not specified
CNA @astrojs Markdoc affected >= 0.3.0, < 2.1.2 Not specified

References

ReferenceSourceLinkTags
github.com/withastro/astro/releases/tag/@astrojs/[email protected] [email protected] github.com
github.com/withastro/astro/security/advisories/GHSA-ff38-p3qj-4pmf [email protected] github.com
github.com/withastro/astro/releases/tag/@astrojs/[email protected] [email protected] github.com
github.com/withastro/astro/commit/edfbf4ab34ff007ae8f7188af76a023a15c9443d [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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