# CVE-2020-28724: Open Redirect in werkzeug

> An attacker can redirect users to malicious sites via a double slash in the URL, affecting applications using the Werkzeug library.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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:** 18 Nov 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-28724, GHSA-3p3h-qghp-hvh2, PYSEC-2020-157, UBUNTU-CVE-2020-28724

## What is CVE-2020-28724?

CVE-2020-28724 is a medium-severity vulnerability in n/a, published on 18 Nov 2020. 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

Open redirect vulnerability in werkzeug before 0.11.6 via a double slash in the URL.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2020-28724?

3 open source packages ship an affected version, including werkzeug. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `werkzeug` | PyPI | All versions | 0.11.6 |
| `werkzeug` | PyPI | All versions | 0.11.6 |
| `werkzeug` | PyPI | All versions | 0.11.6 |

Products: Palletsprojects Werkzeug.

## How do I fix CVE-2020-28724?

Upgrade werkzeug to 0.11.6 or later.

## Is CVE-2020-28724 being exploited?

There is no known exploitation of CVE-2020-28724 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2022-29361](https://insights.sbomify.com/CVE-2022-29361/): Other in n/a (critical 9.8)
- [CVE-2023-46136](https://insights.sbomify.com/CVE-2023-46136/): Werkzeug DoS: High resource usage when parsing multipart/form-data containing a large part with CR/LF character at the beginning (high 8.0)
- [CVE-2023-25577](https://insights.sbomify.com/CVE-2023-25577/): Werkzeug may allow high resource usage when parsing multipart form data with many fields (high 7.5)
- [CVE-2019-14322](https://insights.sbomify.com/CVE-2019-14322/): Pallets Werkzeug vulnerable to Path Traversal (high 7.5)
- [CVE-2026-27199](https://insights.sbomify.com/CVE-2026-27199/): Werkzeug safe_join() allows Windows special device names (medium 6.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-28724 and fix it if it is affected.

What it is: CVE-2020-28724 is a medium-severity vulnerability in n/a, published on 18 Nov 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-28724 in the wild and no public exploit code.

Affected packages and fixed versions:
- werkzeug (PyPI): affected all versions; fixed in 0.11.6
- werkzeug (PyPI): affected all versions; fixed in 0.11.6
- werkzeug (PyPI): affected all versions; fixed in 0.11.6

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-2020-28724/ (Markdown: https://insights.sbomify.com/CVE-2020-28724/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-28724
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-28724
- OSV: https://osv.dev/vulnerability/CVE-2020-28724

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-28724/
Summaries are generated and may contain mistakes; the official description above is the record.