Nuxt is an open-source web development framework for Vue.js. From 3.21.7 until 3.21.10 and 4.5.1, mixed-case routeRules keys can fail to match case-folded lookups when router.options.sensitive is false and drop appMiddleware authorization gates. This is caused by an incomplete fix for CVE-2026-53721. This issue is fixed in 3.21.10 and 4.5.1.