{"id":"GHSA-4633-3j49-mh5q","summary":"Next.js: Cache confusion of response bodies for requests with bodies containing invalid UTF-8 byte sequences","details":"## Impact\n\nA server-side `fetch` with a request body may return a cached **response** body from a different request to the same URL but different body. Confidential data in the `POST`'s **response** body would then leak to unauthorized requests. Though the request itself will not be deduped.\n\nThis is only an issue when receiving request bodies with a content type charset other than UTF-8. For example, the UTF-16 byte sequences for `삃삃` and `섄섄` in the request body would share the same cache.\n\n## Workarounds\n\nIf you cannot upgrade, consider only making fetch requests with UTF-8 bodies (default in Next.js). Applications using Pages Router are not vulnerable.","aliases":["CVE-2026-64647"],"modified":"2026-07-22T23:25:41.220569Z","published":"2026-07-22T23:06:12Z","database_specific":{"cwe_ids":["CWE-116"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-07-22T23:06:12Z","nvd_published_at":null},"references":[{"type":"WEB","url":"https://github.com/vercel/next.js/security/advisories/GHSA-4633-3j49-mh5q"},{"type":"WEB","url":"https://github.com/vercel/next.js/pull/96008"},{"type":"WEB","url":"https://github.com/vercel/next.js/commit/025bf4a5f7b47fb7758c4ebf1c931a61c451c082"},{"type":"PACKAGE","url":"https://github.com/vercel/next.js"},{"type":"WEB","url":"https://github.com/vercel/next.js/releases/tag/v15.5.21"},{"type":"WEB","url":"https://github.com/vercel/next.js/releases/tag/v16.2.11"}],"affected":[{"package":{"name":"next","ecosystem":"npm","purl":"pkg:npm/next"},"ranges":[{"type":"SEMVER","events":[{"introduced":"13.0.0"},{"fixed":"15.5.21"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-4633-3j49-mh5q/GHSA-4633-3j49-mh5q.json"}},{"package":{"name":"next","ecosystem":"npm","purl":"pkg:npm/next"},"ranges":[{"type":"SEMVER","events":[{"introduced":"16.0.0"},{"fixed":"16.2.11"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-4633-3j49-mh5q/GHSA-4633-3j49-mh5q.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N"}]}