# CVE-2017-11156: File upload in Synology Download Station

> Remote authenticated users can execute arbitrary code by uploading an executable due to weak directory permissions in Synology Download Station.

- **Severity:** High 7.8 (`CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Aug 2017
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-qqc7-r2fw-p594

## What is CVE-2017-11156?

CVE-2017-11156 is a high-severity vulnerability in Synology Download Station, published on 14 Aug 2017. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Synology Download Station 3.8.x before 3.8.5-3475 and 3.x before 3.5-2984 uses weak permissions (0777) for ui/dlm/btsearch directory, which allows remote authenticated users to execute arbitrary code by uploading an executable via unspecified vectors.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource), CWE-276 (Incorrect Default Permissions)

## Which versions are affected by CVE-2017-11156?

It affects 1 product.


Products: Synology Download Station.

## How do I fix CVE-2017-11156?

No fix has been published for CVE-2017-11156 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-11156 being exploited?

There is no known exploitation of CVE-2017-11156 in the wild and no public exploit code.

## Other vulnerabilities in Synology Download Station

- [CVE-2021-34809](https://insights.sbomify.com/CVE-2021-34809/): Command injection in Download Station (critical 9.9)
- [CVE-2021-34810](https://insights.sbomify.com/CVE-2021-34810/): Privilege escalation in Download Station (critical 9.9)
- [CVE-2021-33184](https://insights.sbomify.com/CVE-2021-33184/): Server-side request forgery in Synology Download Station (high 7.7)
- [CVE-2017-11149](https://insights.sbomify.com/CVE-2017-11149/): Server-side request forgery in Synology Download Station (medium 6.5)
- [CVE-2021-34811](https://insights.sbomify.com/CVE-2021-34811/): Server-side request forgery in Download Station (medium 5.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-11156 and fix it if it is affected.

What it is: CVE-2017-11156 is a high-severity vulnerability in Synology Download Station, published on 14 Aug 2017. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2017-11156 in the wild and no public exploit code.

Affected product: Synology Download Station. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2017-11156/ (Markdown: https://insights.sbomify.com/CVE-2017-11156/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-11156
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-11156
- OSV: https://osv.dev/vulnerability/CVE-2017-11156

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-11156/
Summaries are generated and may contain mistakes; the official description above is the record.