{"id":"CVE-2026-44575","aliases":["GHSA-267c-6grr-h53f"],"url":"https://o3.security/vulnerability/CVE-2026-44575","summary":"Next.js: 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.","published":"2026-05-13T16:54:39.455Z","modified":"2026-08-15T04:06:58.696484797Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"},"epss":{"score":0.01594,"percentile":0.73815,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"next","fixedVersion":"15.5.16"},{"ecosystem":"npm","name":"next","fixedVersion":"16.2.5"}],"fix":null,"references":[{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44575.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:34608"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:37272"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:40974"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:54435"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-44575"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44575.json"},{"type":"ADVISORY","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":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2477188"},{"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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-15T04:06:58.696484797Z"}}