{"id":"GHSA-36qx-fr4f-26g5","summary":"Next.js has a Middleware / Proxy bypass in Pages Router applications using i18n","details":"### Impact\n\nApplications using the Pages Router with `i18n` configured and middleware/proxy-based authorization can allow unauthorized access to protected page data through locale-less `/_next/data/\u003cbuildId\u003e/\u003cpage\u003e.json` requests. In affected configurations, middleware does not run for the unprefixed data route, allowing an attacker to retrieve SSR JSON for protected pages without passing the intended authorization checks.\n\n### Fix\nThe matcher logic was updated to perform the same match as it would on a non-i18n data route.\n\n### Workarounds\n\nIf you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.","aliases":["CVE-2026-44573"],"modified":"2026-09-10T03:51:04.325298044Z","published":"2026-05-11T15:53:51Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-05-11T15:53:51Z","nvd_published_at":"2026-05-13T17:16:22Z","cwe_ids":["CWE-863"],"severity":"HIGH"},"references":[{"type":"WEB","url":"https://github.com/vercel/next.js/security/advisories/GHSA-36qx-fr4f-26g5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44573"},{"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":"12.2.0"},{"fixed":"15.5.16"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-36qx-fr4f-26g5/GHSA-36qx-fr4f-26g5.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-36qx-fr4f-26g5/GHSA-36qx-fr4f-26g5.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"}]}