{"id":"GHSA-267c-6grr-h53f","summary":"Next.js has a Middleware / Proxy bypass in App Router applications via segment-prefetch routes","details":"### Impact\n\nApp Router applications that rely on middleware or proxy-based checks for authorization can allow unauthorized access through transport-specific route variants used for segment prefetching. In affected configurations, specially crafted `.rsc` and segment-prefetch URLs can resolve to the same page without being matched by the intended middleware rule, which can allow protected content to be reached without the expected authorization check.\n\n### Fix\n\nWe now include App Router transport variants when generating middleware matchers, so middleware protections are applied consistently to those requests as well as to the normal page URL.\n\n### Workarounds\n\nIf you cannot upgrade immediately, enforce authorization in the underlying route or page logic instead of relying solely on middleware.","aliases":["CVE-2026-44575"],"modified":"2026-07-17T21:07:41.685454812Z","published":"2026-05-11T15:54:24Z","database_specific":{"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-05-11T15:54:24Z","nvd_published_at":"2026-05-13T17:16:22Z","cwe_ids":["CWE-288"]},"references":[{"type":"WEB","url":"https://github.com/vercel/next.js/security/advisories/GHSA-267c-6grr-h53f"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44575"},{"type":"PACKAGE","url":"https://github.com/vercel/next.js"},{"type":"WEB","url":"https://github.com/vercel/next.js/releases/tag/v15.5.16"},{"type":"WEB","url":"https://github.com/vercel/next.js/releases/tag/v16.2.5"}],"affected":[{"package":{"name":"next","ecosystem":"npm","purl":"pkg:npm/next"},"ranges":[{"type":"SEMVER","events":[{"introduced":"15.2.0"},{"fixed":"15.5.16"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-267c-6grr-h53f/GHSA-267c-6grr-h53f.json"}},{"package":{"name":"next","ecosystem":"npm","purl":"pkg:npm/next"},"ranges":[{"type":"SEMVER","events":[{"introduced":"16.0.0"},{"fixed":"16.2.5"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-267c-6grr-h53f/GHSA-267c-6grr-h53f.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"}]}