Vite EUVD-2026-105135

Requires a network-reachable Vite dev server running an affected version (8.2.0 through 8.2.3, or 8.3.0 through 8.3.2) - note Vite's dev server defaults to localhost binding, so practical exploitation needs the server exposed to the attacker (e.g. bound to 0.0.0.0, proxied, or on a shared network). The attacker sends a request whose path targets a file outside the server.fs allowed roots with a ?vite-wasm-instance query string, which routes to the internal Wasm plugin's load hook that strips the query and reads from disk without the server.fs restriction. The disclosure only occurs when the targeted file fails WebAssembly parsing (true for virtually all non-.wasm files), causing Node or Deno to throw an error containing the bytes. Strong limiting factors: only the FIRST 4 BYTES of the file are leaked (no full-file read), and the dev server is not meant to be a production/internet-facing surface.

This is a moderate, bounded information-disclosure flaw rather than a top-tier priority. The vendor-supplied CVSS 4.0 vector (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, 6.3) correctly captures the shape of the issue: network-reachable and unauthenticated (PR:N), but with an Attack Requirement (AT:P) and only Low confidentiality impact (VC:L) because the primitive leaks just the first 4 bytes of a targeted file via a WebAssembly parse-error message. There is no EPSS score, no CISA KEV listing, and no public exploit code supplied in the intelligence, so this is 'no public exploit identified at time of analysis' and there is no evidence of active exploitation. A key limiting factor not fully reflected in AV:N is that the affected component is the Vite development server, which by default binds to localhost and is not intended to be internet-exposed - so the network vector is realistic mainly where a dev server is deliberately or accidentally exposed. The source diff confirms the root cause and fix (adding wasmInstanceRE to the guard in transform.ts so ?vite-wasm-instance requests undergo the same restriction as ?raw/?url/?inline/?svg, returning 403), which strengthens confidence in the mechanism. Net: a genuine but low-severity, narrow-primitive leak; prioritize patching dev tooling but it does not warrant emergency response absent exposure.

A developer runs a Vite dev server (8.2.0-8.2.3 or 8.3.0-8.3.2) that is reachable by an attacker - for example bound to 0.0.0.0 on a shared network or proxied externally. The attacker requests a sensitive file outside the allowed server.fs roots with a ?vite-wasm-instance query (e.g. /root/src/.env?vite-wasm-instance); Vite's internal Wasm plugin reads it without the fs check, fails to parse it as WebAssembly, and the thrown Node/Deno error echoes the file's first 4 bytes back to the attacker. No public exploit code was provided, though the fix commit and test cases make the technique straightforward to reproduce.