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High, CVSS 8.8amended

Nuxt: Route-rule middleware bypass via case-sensitivity mismatch between vue-router and the routeRules matcher

CVE-2026-53721GHSA-mm7m-92g8-7m47

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (nuxt 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.

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Affected packages

  • npm nuxt

    Affected
    >= 4.0.0, < 4.4.7>= 3.11.0, < 3.21.7
    Fixed in
    4.4.7, 3.21.7

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.8 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-53721: 0.40% estimated exploitation activity in the next 30 days; percentile 34.19 (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.

Impact Nuxt looks up routeRules for the current navigation by calling getRouteRules({ path: to.path }) from the page-router plugin and the no-pages router plugin. The compiled routeRules matcher (built on rou3) performs case-sensitive matching, while vue-router is configured with its default sensitive: false and matches paths case-insensitively. The two routers therefore disagree on which rules apply to a given request path: vue-router still matches the page record for /Admin/dashboard, but the routeRules lookup for the same path returns no match. Any appMiddleware declared via routeRules is never added to the middleware set and never runs, on both SSR and client navigations. The same path skips other path-keyed route rules in the same way (ssr, redirect, appLayout, and the prerender / payload hints used client-side). For applications using routeRules with appMiddleware as an authorization gate (a documented pattern), an attacker can flip the case of any static segment in a protected…

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

    Amended from ghsa record GHSA-mm7m-92g8-7m47

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-mm7m-92g8-7m47

Agent brief

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# Patch Next advisory brief: CVE-2026-53721

Advisory: Nuxt: Route-rule middleware bypass via case-sensitivity mismatch between vue-router and the routeRules matcher
IDs: CVE-2026-53721, GHSA-mm7m-92g8-7m47
Record: https://patchnext.com/advisories/cve-2026-53721 (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: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nuxt 4.4.7, 3.21.7. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm nuxt: affected >= 4.0.0, < 4.4.7; >= 3.11.0, < 3.21.7; fixed in 4.4.7, 3.21.7

## Suggested inspection (read-only)
- `npm ls nuxt --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.
- 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-mm7m-92g8-7m47 (OSV record GHSA-mm7m-92g8-7m47 lists affected ranges: npm nuxt >=4.0.0 =3.11.0 <3.21.7 (fixed))
- Verified: https://github.com/advisories/GHSA-mm7m-92g8-7m47 (GitHub-reviewed advisory GHSA-mm7m-92g8-7m47 lists affected ranges: npm nuxt >=4.0.0 =3.11.0 <3.21.7)

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