# CVE-2017-1000420: Syncthing vulnerable to symlink traversal and arbitrary file overwrite

> Attackers can exploit symlink traversal in Syncthing to overwrite arbitrary files on the system.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Jan 2018
- **Updated:** 16 Sep 2024
- **Also known as:** DEBIAN-CVE-2017-1000420, GHSA-28xp-g7f6-7mhf

## What is CVE-2017-1000420?

CVE-2017-1000420 is a high-severity path traversal vulnerability in n/a, published on 2 Jan 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Syncthing version 0.14.33 and older is vulnerable to symlink traversal resulting in arbitrary file overwrite

Weakness: CWE-59 (Improper Link Resolution Before File Access)

## Which versions are affected by CVE-2017-1000420?

2 open source packages ship an affected version, including github.com/syncthing/syncthing. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/syncthing/syncthing` | Go | All versions to 0.14.33 | None |
| `github.com/syncthing/syncthing` | Go | All versions to 0.14.33 | None |

Products: Syncthing Syncthing.

## How do I fix CVE-2017-1000420?

Upgrade to a fixed version.

## Is CVE-2017-1000420 being exploited?

There is no known exploitation of CVE-2017-1000420 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-21404](https://insights.sbomify.com/CVE-2021-21404/): Crash due to malformed relay protocol message (high 7.5)
- [CVE-2022-46165](https://insights.sbomify.com/CVE-2022-46165/): Cross-site Scripting (XSS) in Web GUI in syncthing (medium 4.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-1000420 and fix it if it is affected.

What it is: CVE-2017-1000420 is a high-severity path traversal vulnerability in n/a, published on 2 Jan 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2017-1000420 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/syncthing/syncthing (Go): affected all versions up to 0.14.33; no fix listed
- github.com/syncthing/syncthing (Go): affected all versions up to 0.14.33; no fix listed

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-2017-1000420/ (Markdown: https://insights.sbomify.com/CVE-2017-1000420/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-1000420
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-1000420
- OSV: https://osv.dev/vulnerability/CVE-2017-1000420

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-1000420/
Summaries are generated and may contain mistakes; the official description above is the record.