CVE-2026-126365

MEDIUMCVSS 5.4/10

Last modified

CVE-2026-126365 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. Astro 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.

Description

Astro 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.

Metrics

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
withastroastro< 7.4.3
@astrojsprism< 4.1.2
@astrojsmarkdoc>= 0.3.0, < 2.1.2

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-126365?
Astro 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.
How severe is CVE-2026-126365?
CVE-2026-126365 has a CVSS score of 5.4/10 (MEDIUM severity).
How do I fix CVE-2026-126365?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST