# CVE-2026-59149: Mockoon: Path traversal in templated `filePath` lets a request escape the served directory (prefix-only base check)

> An unauthenticated attacker can read files outside the served directory in Mockoon due to a flawed path validation check.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 9 Jul 2026
- **Updated:** 9 Jul 2026
- **Also known as:** GHSA-8wqc-v2q8-vff2

## What is CVE-2026-59149?

CVE-2026-59149 is a medium-severity path traversal vulnerability in mockoon, published on 9 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Mockoon provides way to design and run mock APIs. Prior to 9.7.0, a FILE response whose filePath embeds request data is confined by getSafeFilePath in packages/commons-server/src/libs/server/server.ts 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, allowing an unauthenticated client to read files from sibling paths outside the served directory through HTTP sendFile, WebSocket, or callbacks. This issue is fixed in version 9.7.0.

Weakness: CWE-23 (Relative Path Traversal), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-59149?

4 open source packages ship an affected version, including @mockoon/cli and @mockoon/commons-server.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@mockoon/cli` | npm | All versions | 9.7.0 |
| `@mockoon/cli` | npm | All versions | 9.7.0 |
| `@mockoon/commons-server` | npm | All versions | 9.7.0 |
| `@mockoon/commons-server` | npm | All versions | 9.7.0 |

## How do I fix CVE-2026-59149?

Upgrade @mockoon/cli to 9.7.0 or later.

## Is CVE-2026-59149 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59149 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-59149 and fix it if it is affected.

What it is: CVE-2026-59149 is a medium-severity path traversal vulnerability in mockoon, published on 9 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59149 exists.

Affected packages and fixed versions:
- @mockoon/cli (npm): affected all versions; fixed in 9.7.0
- @mockoon/cli (npm): affected all versions; fixed in 9.7.0
- @mockoon/commons-server (npm): affected all versions; fixed in 9.7.0
- @mockoon/commons-server (npm): affected all versions; fixed in 9.7.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-59149/ (Markdown: https://insights.sbomify.com/CVE-2026-59149/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-59149
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-59149
- OSV: https://osv.dev/vulnerability/CVE-2026-59149

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-59149/
Summaries are generated and may contain mistakes; the official description above is the record.