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Medium, CVSS 6.5amended

Astro: Unauthenticated path override in the @astrojs/vercel ISR function

CVE-2026-73424GHSA-x27w-589x-frm2

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (@astrojs/vercel 11.0.3), 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

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:N/S:U/C:L/I:L/A:N
EPSS
  • CVE-2026-73424: 0.38% estimated exploitation activity in the next 30 days; percentile 32.51 (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 When ISR is enabled, the serverless entrypoint lets an unauthenticated request decide which route the origin renders. The internal isr function reads the xastropath query parameter and rewrites the request path to it without any authentication. Edge level access controls only ever see the /isr path, so they do not apply to the route that actually gets rendered. This is the same confused deputy problem as CVE-2026-33768, reachable again through the ISR path. Impact This affects apps that use @astrojs/vercel with isr: true and protect routes at the edge. Two common setups are affected: 1. Path rules or firewall deny rules configured on Vercel (for example blocking /admin). 2. Split deployments (edgeMiddleware: true) where authorization lives in Astro middleware, since that middleware runs at the edge and not in the origin. An attacker reads any GET rendered route by requesting /isr?xastropath=/the/protected/path. No credentials are required. The protected content is produced by…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-x27w-589x-frm2

  2. Revision 1 · created ·

    Published from osv record GHSA-x27w-589x-frm2

Agent brief

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# Patch Next advisory brief: CVE-2026-73424

Advisory: Astro: Unauthenticated path override in the @astrojs/vercel ISR function
IDs: CVE-2026-73424, GHSA-x27w-589x-frm2
Record: https://patchnext.com/advisories/cve-2026-73424 (revision 2, source checked 26 Oct 2026, 13:01 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: @astrojs/vercel 11.0.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @astrojs/vercel: affected >= 10.0.3, < 11.0.3; fixed in 11.0.3

## Suggested inspection (read-only)
- `npm ls @astrojs/vercel --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 @astrojs/vercel.
- 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://osv.dev/vulnerability/GHSA-x27w-589x-frm2 (OSV record GHSA-x27w-589x-frm2 lists affected ranges: npm @astrojs/vercel >=10.0.3 <11.0.3 (fixed))
- Verified: https://github.com/advisories/GHSA-x27w-589x-frm2 (GitHub-reviewed advisory GHSA-x27w-589x-frm2 lists affected ranges: npm @astrojs/vercel >=10.0.3 <11.0.3)

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