# CVE-2020-12666: gopkg.in/macaron.v1 Open Redirect vulnerability

> An open redirect vulnerability in the macaron Go library allows attackers to redirect users to malicious sites via crafted URLs.

- **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:** 5 May 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-733f-44f3-3frw, GO-2020-0039

## What is CVE-2020-12666?

CVE-2020-12666 is a medium-severity vulnerability in Fedoraproject Fedora, published on 5 May 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

macaron before 1.3.7 has an open redirect in the static handler, as demonstrated by the http://127.0.0.1:4000//example.com/ URL.

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

## Which versions are affected by CVE-2020-12666?

3 open source packages ship an affected version, including gopkg.in/macaron.v1. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `gopkg.in/macaron.v1` | Go | All versions | 1.3.7 |
| `gopkg.in/macaron.v1` | Go | All versions | 1.3.7 |
| `gopkg.in/macaron.v1` | Go | All versions | 1.3.7 |

Products: Fedoraproject Fedora, Go-Macaron Macaron.

## How do I fix CVE-2020-12666?

Upgrade gopkg.in/macaron.v1 to 1.3.7 or later.

## Is CVE-2020-12666 being exploited?

There is no known exploitation of CVE-2020-12666 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-12666 and fix it if it is affected.

What it is: CVE-2020-12666 is a medium-severity vulnerability in Fedoraproject Fedora, published on 5 May 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-2020-12666 in the wild and no public exploit code.

Affected packages and fixed versions:
- gopkg.in/macaron.v1 (Go): affected all versions; fixed in 1.3.7
- gopkg.in/macaron.v1 (Go): affected all versions; fixed in 1.3.7
- gopkg.in/macaron.v1 (Go): affected all versions; fixed in 1.3.7

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-2020-12666/ (Markdown: https://insights.sbomify.com/CVE-2020-12666/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-12666
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-12666
- OSV: https://osv.dev/vulnerability/CVE-2020-12666

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-12666/
Summaries are generated and may contain mistakes; the official description above is the record.