{"cve":"CVE-2026-29057","nvd":{"published":"2026-03-18T01:16:05.443","modified":"2026-06-17T10:29:31.380","status":"Analyzed","description":"Next.js is a React framework for building full-stack web applications. Starting in version 9.5.0 and prior to versions 15.5.13 and 16.1.7, when Next.js rewrites proxy traffic to an external backend, a crafted `DELETE`/`OPTIONS` request using `Transfer-Encoding: chunked` could trigger request boundary disagreement between the proxy and backend. This could allow request smuggling through rewritten routes. An attacker could smuggle a second request to unintended backend routes (for example, internal/admin endpoints), bypassing assumptions that only the configured rewrite destination/path is reachable. This does not impact applications hosted on providers that handle rewrites at the CDN level, such as Vercel.  The vulnerability originated in an upstream library vendored by Next.js. It is fixed in Next.js 15.5.13 and 16.1.7 by updating that dependency’s behavior so `content-length: 0` is added only when both `content-length` and `transfer-encoding` are absent, and `transfer-encoding` is no longer removed in that code path. If upgrading is not immediately possible, block chunked `DELETE`/`OPTIONS` requests on rewritten routes at the edge/proxy, and/or enforce authentication/authorization on backend routes.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","score":6.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","score":6.5},"cwes":["CWE-444"],"references":["https://github.com/vercel/next.js/commit/dc98c04f376c6a1df76ec3e0a2d07edf4abdabd6","https://github.com/vercel/next.js/releases/tag/v15.5.13","https://github.com/vercel/next.js/releases/tag/v16.1.7","https://github.com/vercel/next.js/security/advisories/GHSA-ggv3-7p47-pfv8"],"products":["vercel:next.js"],"source":"nvd","synced_at":"2026-10-19T22:26:19.218427112+00:00"},"epss":{"cve":"CVE-2026-29057","score":0.00453,"percentile":0.39386,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-ggv3-7p47-pfv8","url":"https://osv.dev/vulnerability/GHSA-ggv3-7p47-pfv8","summary":"Next.js: HTTP request smuggling in rewrites","modified":"2026-09-10T03:50:39.201962373Z","packages":[{"ecosystem":"npm","name":"next","purl":"pkg:npm/next","ranges":[">=16.0.0-beta.0 <16.1.7"],"fixed":["16.1.7"]},{"ecosystem":"npm","name":"next","purl":"pkg:npm/next","ranges":[">=9.5.0 <15.5.13"],"fixed":["15.5.13"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}