{"id":"CVE-2026-119201","aliases":["GHSA-3xf4-9g3c-4h4w"],"url":"https://o3.security/vulnerability/CVE-2026-119201","summary":"Nuxt dev server exposes generated appSecret through Vite file serving","details":"### Impact\n\nWhen no `appSecret` is configured (via `NUXT_APP_SECRET`, `NITRO_APP_SECRET` or `runtimeConfig.appSecret`), `nuxt dev` generates a development secret and stores it in `<buildDir>/app-secret` (by default `.nuxt/app-secret`). The build directory is inside the directories that Nuxt passes to Vite's `server.fs.allow`, so the file can be fetched from the dev server:\n\n```bash\ncurl http://<dev-server>/_nuxt/@fs/<absolute-path-to-project>/.nuxt/app-secret\n```\n\nAnyone who can read it can compute every secret derived from it with `deriveSecret()`, including the default password used by `useSession`, and so can forge session cookies accepted by that dev server.\n\nExploitation requires direct HTTP access to the dev server. `nuxt dev` listens on localhost by default, so this mainly affects dev servers that are exposed to a network (for example with `--host`, a published container port or a tunnel). A malicious website cannot read the file through a developer's browser: Vite's CORS and host checks prevent pages on other origins from reading the response.\n\nProduction builds never generate an `appSecret` and are not affected. Dev servers with an explicitly configured `appSecret` do not use the generated file.\n\n### Patches\n\nFixed in `@nuxt/vite-builder` 4.6.3, which `nuxt` 4.6.3 depends on. The dev server now adds `app-secret` to Vite's `server.fs.deny`, keeping Vite's default deny list.\n\n### Workarounds\n\nSet `NUXT_APP_SECRET` in `.env` to a random value of at least 32 characters (for example the output of `openssl rand -base64 32`), or avoid exposing the dev server to untrusted networks.\n\nIf a dev server using a generated secret has been reachable by untrusted clients, delete `.nuxt/app-secret` (a new secret is generated on the next `nuxt dev`) or set `NUXT_APP_SECRET`. Either invalidates existing dev sessions.","published":"2026-10-29T20:21:27.895Z","modified":"2026-10-31T02:47:37.223324087Z","cvss":{"score":4.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"@nuxt/vite-builder","fixedVersion":"4.6.3"}],"fix":{"url":"https://github.com/nuxt/nuxt/commit/2981290f36d9c5412c022758f3d89ba21a845308","label":"nuxt/nuxt@2981290"},"references":[{"type":"WEB","url":"https://github.com/nuxt/nuxt/releases/tag/v4.6.3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/119xxx/CVE-2026-119201.json"},{"type":"ADVISORY","url":"https://github.com/nuxt/nuxt/security/advisories/GHSA-3xf4-9g3c-4h4w"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-119201"},{"type":"FIX","url":"https://github.com/nuxt/nuxt/commit/2981290f36d9c5412c022758f3d89ba21a845308"},{"type":"FIX","url":"https://github.com/nuxt/nuxt/commit/545004cc350be7003dea4116ce6206d6f980b1fd"},{"type":"PACKAGE","url":"https://github.com/nuxt/nuxt"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-31T02:47:37.223324087Z"}}