Astro: Unauthenticated Path Override via x-astro-path / x_astro_path

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-2026-33768: 0.34% estimated exploitation activity in the next 30 days; percentile 27.95 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The @astrojs/vercel serverless entrypoint reads the x-astro-path header and xastropath query parameter to rewrite the internal request path, with no authentication whatsoever. On deployments without Edge Middleware, this lets anyone bypass Vercel's platform-level path restrictions entirely. The override preserves the original HTTP method and body, so this isn't limited to GET. POST, PUT, DELETE all land on the rewritten path. A Firewall rule blocking /admin/ does nothing when the request comes in as POST /api/health?xastropath=/admin/delete-user. Affected Versions Verified against: - Astro 5.18.1 + @astrojs/vercel 9.0.4 — GET and POST override both work. Full exploitation. - Astro 6.0.3 + @astrojs/vercel 10.0.0 — GET override works. POST/DELETE hit a duplex bug in the Request constructor (the duplex: 'half' option is required when passing a ReadableStream body — this has been an issue since Node.js 18 but is consistently enforced in the Node.js 22+ runtime that Astro 6…

Published by the source

26 Mar 2026, 18:41 UTC

Last modified by the source

26 Mar 2026, 18:56 UTC

Source last checked

26 Oct 2026, 12:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mr6q-rp88-fx84

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mr6q-rp88-fx84

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

# Patch Next advisory brief: CVE-2026-33768

Advisory: Astro: Unauthenticated Path Override via `x-astro-path` / `x_astro_path`
IDs: CVE-2026-33768, GHSA-mr6q-rp88-fx84
Record: https://patchnext.com/advisories/cve-2026-33768 (revision 2, source checked 26 Oct 2026, 12:46 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 10.0.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @astrojs/vercel: affected < 10.0.2; fixed in 10.0.2

## 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-mr6q-rp88-fx84 (OSV record GHSA-mr6q-rp88-fx84 lists affected ranges: npm @astrojs/vercel >=0 <10.0.2 (fixed))
- Verified: https://github.com/advisories/GHSA-mr6q-rp88-fx84 (GitHub-reviewed advisory GHSA-mr6q-rp88-fx84 lists affected ranges: npm @astrojs/vercel >=0 <10.0.2)

Commands are suggestions: review each one before running it.