# CVE-2020-27304: Path traversal in civetweb

> Attackers can exploit directory traversal in CivetWeb's file upload handler to read or modify arbitrary files on non-Windows systems.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Oct 2021
- **Updated:** 4 Aug 2024
- **Also known as:** AZL-39076, DEBIAN-CVE-2020-27304, GHSA-wphm-mh7c-38cf, UBUNTU-CVE-2020-27304, openSUSE-SU-2021:1424-1

## What is CVE-2020-27304?

CVE-2020-27304 is a critical path traversal vulnerability in Siemens Sinec Infrastructure Network Services, published on 21 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when using the built-in HTTP form-based file upload mechanism, via the mg_handle_form_request API. Web applications that use the file upload form handler, and use parts of the user-controlled filename in the output path, are susceptible to directory traversal

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

## Which versions are affected by CVE-2020-27304?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `civetweb` | openSUSE:Leap 15.2 | All versions | 1.15-lp152.2.3.1 |

Products: Civetweb Project Civetweb, Siemens Sinec Infrastructure Network Services.

## How do I fix CVE-2020-27304?

Upgrade to a fixed version.

## Is CVE-2020-27304 being exploited?

There is no known exploitation of CVE-2020-27304 in the wild and no public exploit code.

## Other vulnerabilities in Siemens Sinec Infrastructure Network Services

- [CVE-2026-5789](https://insights.sbomify.com/CVE-2026-5789/): Search path without quotes in CivetWeb (high 8.5)
- [CVE-2025-55763](https://insights.sbomify.com/CVE-2025-55763/): Memory corruption in n/a (high 7.5)
- [CVE-2018-12684](https://insights.sbomify.com/CVE-2018-12684/): Information disclosure in n/a (high 7.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-27304 and fix it if it is affected.

What it is: CVE-2020-27304 is a critical path traversal vulnerability in Siemens Sinec Infrastructure Network Services, published on 21 Oct 2021. 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-2020-27304 in the wild and no public exploit code.

Affected product: Siemens Sinec Infrastructure Network Services. 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-2020-27304/ (Markdown: https://insights.sbomify.com/CVE-2020-27304/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-27304
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-27304
- OSV: https://osv.dev/vulnerability/CVE-2020-27304

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-27304/
Summaries are generated and may contain mistakes; the official description above is the record.