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Medium, CVSS 6.5amended

Astro: Reflected/Stored XSS via unescaped / tag content in JSX/MDX rendering

CVE-2026-114128GHSA-98hj-9722-w3j8

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (astro 7.3.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm astro

    Affected
    < 7.3.2
    Fixed in
    7.3.2

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
EPSS
  • CVE-2026-114128: 0.32% estimated exploitation activity in the next 30 days; percentile 25.16 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Astro's JSX and MDX rendering pipeline treated string children of <script and <style elements as trusted HTML. When a dynamic value was passed through a JSX expression, such as <script{value}</script, an attacker-controlled value containing </script or </style could terminate the element and inject arbitrary HTML and JavaScript. Other JSX expression contexts escaped dynamic strings automatically. This behavior was limited to <script and <style children rendered through Astro's astro:jsx renderer, including MDX components. Details The affected rendering paths marked all string children of <script and <style elements as safe HTML, without distinguishing literal content generated by the compiler from dynamic expression values. An application was vulnerable when attacker-controlled data, such as a query parameter or CMS field, was interpolated directly into one of these elements. For example, a value containing </script<scriptalert(1)</script passed to <script{value}</script was…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-98hj-9722-w3j8

  2. Revision 2 · amended ·

    Amended from osv record GHSA-98hj-9722-w3j8

  3. Revision 1 · created ·

    Published from ghsa record GHSA-98hj-9722-w3j8

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-114128

Advisory: Astro: Reflected/Stored XSS via unescaped / tag content in JSX/MDX rendering
IDs: CVE-2026-114128, GHSA-98hj-9722-w3j8
Record: https://patchnext.com/advisories/cve-2026-114128 (revision 3, source checked 26 Oct 2026, 13:07 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: astro 7.3.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm astro: affected < 7.3.2; fixed in 7.3.2

## Suggested inspection (read-only)
- `npm ls astro --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on astro.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-98hj-9722-w3j8 (GitHub-reviewed advisory GHSA-98hj-9722-w3j8 lists affected ranges: npm astro >=0 <7.3.2)
- Verified: https://osv.dev/vulnerability/GHSA-98hj-9722-w3j8 (OSV record GHSA-98hj-9722-w3j8 lists affected ranges: npm astro >=0 <7.3.2 (fixed))

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