Answer in brief
CVE-2026-126365 records a Medium severity (CVSS 5.4) vulnerability in Astro: XSS via unescaped code for unsupported languages in @astrojs/prism. The current sources do not mark it as known exploited. The current feed maps withastro/astro (generic), @astrojs/markdoc (generic), @astrojs/prism (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps withastro/astro (generic), @astrojs/markdoc (generic), @astrojs/prism (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| withastro/astrogeneric | <7.4.3 | 7.4.3 |
| @astrojs/markdocgeneric | >=0.3.0 <2.1.2 | 2.1.2 |
| @astrojs/prismgeneric | <4.1.2 | 4.1.2 |
Published upstream
Nov 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 12, 2026
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.
Quoted source text, attributed separately from HOL analysis.