CVE-2026-112947: Vite: First 4 bytes of files outside of `server.fs` setting is exposed by `?vite-wasm-instance`

Severity: medium (CVSS 6.3 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-20 · updated 2026-10-21
Weakness: CWE-22

Description

Vite is a frontend tooling framework for JavaScript. From 8.2.0 until 8.2.4 and 8.3.3, the first 4 bytes of files outside of server.fs setting can be returned to the browser by a request containing ?vite-wasm-instance. 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. This vulnerability is fixed in 8.2.4 and 8.3.3.

Affected products

Npm Vite: from 8.3.0 before 8.3.3; from 8.2.0 before 8.2.4 — fixed in 8.3.3, 8.2.4
Npm Vite-Plus: from 0.2.8 before 1.1.0 — fixed in 1.1.0
vitejs vite: from 8.3.0, < 8.3.3; from 8.2.0, < 8.2.4
vitejs vite-plus: from 0.2.8, < 1.1.0

How to fix

Upgrade to a fixed version: Npm Vite 8.3.3, 8.2.4; Npm Vite-Plus 1.1.0. Check the vendor advisory for mitigations.

References

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