{"id":"GHSA-mq59-m269-xvcx","summary":"Next.js: null origin can bypass Server Actions CSRF checks","details":"## Summary\n`origin: null` was treated as a \"missing\" origin during Server Action CSRF validation. As a result, requests from opaque contexts (such as sandboxed iframes) could bypass origin verification instead of being validated as cross-origin requests.\n\n## Impact\nAn attacker could induce a victim browser to submit Server Actions from a sandboxed context, potentially executing state-changing actions with victim credentials (CSRF).\n\n## Patches\nFixed by treating `'null'` as an explicit origin value and enforcing host/origin checks unless `'null'` is explicitly allowlisted in `experimental.serverActions.allowedOrigins`.  \n\n## Workarounds\nIf upgrade is not immediately possible:\n- Add CSRF tokens for sensitive Server Actions.\n- Prefer `SameSite=Strict` on sensitive auth cookies.\n- Do not allow `'null'` in `serverActions.allowedOrigins` unless intentionally required and additionally protected.","aliases":["CVE-2026-27978"],"modified":"2026-03-19T18:34:30.603117Z","published":"2026-03-17T15:30:14Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-03-17T15:30:14Z","nvd_published_at":"2026-03-18T00:16:20Z","cwe_ids":["CWE-352"],"severity":"MODERATE"},"references":[{"type":"WEB","url":"https://github.com/vercel/next.js/security/advisories/GHSA-mq59-m269-xvcx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27978"},{"type":"WEB","url":"https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8"},{"type":"PACKAGE","url":"https://github.com/vercel/next.js"},{"type":"WEB","url":"https://github.com/vercel/next.js/releases/tag/v16.1.7"}],"affected":[{"package":{"name":"next","ecosystem":"npm","purl":"pkg:npm/next"},"ranges":[{"type":"SEMVER","events":[{"introduced":"16.0.1"},{"fixed":"16.1.7"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-mq59-m269-xvcx/GHSA-mq59-m269-xvcx.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"}]}