Vite: First 4 bytes of files outside of `server.fs` setting is exposed by `?vite-wasm-instance`

{
  "id": "f12e695aeda1b35d04e2c0aeb62302a87c810e6a4e52c418f869583f90f2258e",
  "url": "https://osv.dev/vulnerability/GHSA-vfpm-58rq-9qcg",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Vite: First 4 bytes of files outside of `server.fs` setting is exposed by `?vite-wasm-instance`",
    "summary": "### Summary The first 4 bytes of files outside of `server.fs` setting can be returned to the browser by a request containing `?vite-wasm-instance`. ### Impact Only apps that match one of the following conditions are affected: - explicitly expose the Vite dev server to the network using `--host` or the [`server.host`](https://vite.dev/config/server-options#server-host) option - there's a file that has a sensitive information in **the first 4 bytes** - uses Node.js or Deno to run Vite (if Bun is used, it is not affected) ### Details Requests containing the `?vite-wasm-instance` query are handled by the internal Wasm plugin's `load` hook. The hook removes the query and reads the resulting path directly from disk, but the `server.fs` checks were not applied. After reading the file, Vite attempts to parse it as WebAssembly. When that parse fails, Node and deno throws an error that contains the first 4 bytes of the file. ### PoC Create a denied file and start an affected Vite dev server: ```bash echo 'SECRET_KEY=abc123\\n' > .env npm run dev curl 'http://localhost:5173/.env?vite-wasm-instance' ``` This will show ``` Failed to parse WASM file \"/.env\": WebAssembly.compile(): expected magic word 00 61 73 6d, found 53 45 43 52 @+0 ```",
    "evidence": "osv:GHSA-vfpm-58rq-9qcg",
    "products": [
      {
        "name": {
          "value": "vite",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "8.3.3",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "vite",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "8.2.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "vite-plus",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.1.0",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-vfpm-58rq-9qcg",
      "aliases": [
        "CVE-2026-112947",
        "GHSA-vfpm-58rq-9qcg"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "8.3.0"
                },
                {
                  "fixed": "8.3.3"
                }
              ]
            }
          ],
          "package": {
            "name": "vite",
            "purl": "pkg:npm/vite",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-vfpm-58rq-9qcg/GHSA-vfpm-58rq-9qcg.json",
            "last_known_affected_version_range": "<= 8.3.2"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "8.2.0"
                },
                {
                  "fixed": "8.2.4"
                }
              ]
            }
          ],
          "package": {
            "name": "vite",
            "purl": "pkg:npm/vite",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-vfpm-58rq-9qcg/GHSA-vfpm-58rq-9qcg.json",
            "last_known_affected_version_range": "<= 8.2.3"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.2.8"
                },
                {
                  "fixed": "1.1.0"
                }
              ]
            }
          ],
          "package": {
            "name": "vite-plus",
            "purl": "pkg:npm/vite-plus",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-vfpm-58rq-9qcg/GHSA-vfpm-58rq-9qcg.json",
            "last_known_affected_version_range": "<= 1.0.0"
          }
        }
      ],
      "modified": "2026-10-21T17:00:07.443467820Z",
      "provider": "osv",
      "references": [
        "https://github.com/vitejs/vite/security/advisories/GHSA-vfpm-58rq-9qcg",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-112947",
        "https://github.com/vitejs/vite/pull/23655",
        "https://github.com/vitejs/vite/commit/b6c6d2fb3f853aab4092dc25f0d6816a96c23dff",
        "https://github.com/vitejs/vite/commit/ba8b7ab43b4afa5d0292ab4b6e3a7b5033cc9c73",
        "https://github.com/vitejs/vite"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-200",
          "CWE-209",
          "CWE-22"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-20T16:17:05Z",
        "github_reviewed_at": "2026-10-21T16:47:15Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-112947",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 394548,
  "published_at": "2026-10-21T16:47:15+00:00"
}