@nuxt/webpack-builder and @nuxt/rspack-builder dev server same-origin check bypassed when Sec-Fetch-Site, Origin, and Referer are all absent (incomplete fix for GHSA-6m52-m754-pw2g)
CVE-2026-49993GHSA-x6qj-4h56-5rj5
What to do
Vendor fix available. Upgrade each affected package to the fixed version on its release line (@nuxt/rspack-builder 4.4.7, 3.21.7; @nuxt/webpack-builder 4.4.7, 3.21.7), 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.
Affected packages
- Affected
- >= 4.0.0, < 4.4.7>= 3.15.4, < 3.21.7
- Fixed in
- 4.4.7, 3.21.7
- Affected
- >= 4.0.0, < 4.4.7>= 3.15.4, < 3.21.7
- Fixed in
- 4.4.7, 3.21.7
Sources
- Open Source Vulnerabilities (OSV.dev), including the GitHub Advisory Database
OSV record GHSA-x6qj-4h56-5rj5 lists affected ranges: npm @nuxt/webpack-builder >=4.0.0 =3.15.4 =4.0.0 =3.15.4 <3.21.7 (fixed)
VerifiedObserved Structured OSV record; GitHub-reviewed advisory.
- GitHub Advisory Database and maintainer security advisories on GitHub
GitHub-reviewed advisory GHSA-x6qj-4h56-5rj5 lists affected ranges: npm @nuxt/webpack-builder >=4.0.0 =3.15.4 =4.0.0 =3.15.4 <3.21.7
VerifiedObserved Structured GitHub Advisory Database record (type=reviewed) from the GitHub REST API.
Severity and exploitation
- Exploitation
- No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
- CVSS 4.0
- 5.9 · CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N · score source
- EPSS
- CVE-2026-49993: 0.28% estimated exploitation activity in the next 30 days; percentile 20.60 (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 This is an incomplete fix for GHSA-6m52-m754-pw2g. Source code may still be stolen during dev when using the webpack / rspack builder if the dev server is bound to a non-loopback address (e.g. nuxt dev --host) and the developer opens a malicious site on the same network. Details The fix for GHSA-6m52-m754-pw2g added an Origin / Referer fallback to the dev-middleware same-origin check, with a return true branch when neither header is present so that non-browser clients (curl, the HMR client, address-bar navigation) keep working. That fallback is bypassed when a cross-origin attacker request reaches the dev server with all three signal headers absent: - Sec-Fetch-Site is not sent by browsers to non-potentially-trustworthy destinations (HTTP on a non-loopback address). - Origin is not sent on non-CORS subresource fetches (a bare <script with no crossorigin). - Referer can be suppressed by the attacker page with <meta name="referrer" content="no-referrer" or…
Dates and revisions
- Published by the source
- Last modified by the source
- Source last checked
- Revision 3 · amended ·
Amended from ghsa record GHSA-x6qj-4h56-5rj5
- Revision 2 · amended ·
Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.
- Revision 1 · created ·
Published from osv record GHSA-x6qj-4h56-5rj5
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-2026-49993 Advisory: @nuxt/webpack-builder and @nuxt/rspack-builder dev server same-origin check bypassed when Sec-Fetch-Site, Origin, and Referer are all absent (incomplete fix for GHSA-6m52-m754-pw2g) IDs: CVE-2026-49993, GHSA-x6qj-4h56-5rj5 Record: https://patchnext.com/advisories/cve-2026-49993 (revision 3, source checked 26 Oct 2026, 12:55 UTC) Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected. Severity: Medium (CVSS 5.9) Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV. Vendor response: Vendor fix available; fixed versions by package: @nuxt/rspack-builder 4.4.7, 3.21.7; @nuxt/webpack-builder 4.4.7, 3.21.7. A vendor fix does not mean a deployment is fixed. ## Affected components - npm @nuxt/rspack-builder: affected >= 4.0.0, < 4.4.7; >= 3.15.4, < 3.21.7; fixed in 4.4.7, 3.21.7 - npm @nuxt/webpack-builder: affected >= 4.0.0, < 4.4.7; >= 3.15.4, < 3.21.7; fixed in 4.4.7, 3.21.7 ## Suggested inspection (read-only) - `npm ls @nuxt/rspack-builder --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`. - `npm ls @nuxt/webpack-builder --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 @nuxt/rspack-builder, @nuxt/webpack-builder. - 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-x6qj-4h56-5rj5 (OSV record GHSA-x6qj-4h56-5rj5 lists affected ranges: npm @nuxt/webpack-builder >=4.0.0 =3.15.4 =4.0.0 =3.15.4 <3.21.7 (fixed)) - Verified: https://github.com/advisories/GHSA-x6qj-4h56-5rj5 (GitHub-reviewed advisory GHSA-x6qj-4h56-5rj5 lists affected ranges: npm @nuxt/webpack-builder >=4.0.0 =3.15.4 =4.0.0 =3.15.4 <3.21.7) Commands are suggestions: review each one before running it.
Loading voting…