# CVE-2020-12137: Cross-site scripting in n/a

> An attacker can execute arbitrary JavaScript in the context of list-archive visitors by exploiting MIME sniffing issues in GNU Mailman.

- **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:** 24 Apr 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DLA-2200-1, DSA-4664-1, GHSA-7mvx-jp9h-p8gh, RHSA-2020:4667, SUSE-SU-2020:14356-1, UBUNTU-CVE-2020-12137

## What is CVE-2020-12137?

CVE-2020-12137 is a medium-severity cross-site scripting vulnerability in Canonical Ubuntu Linux, published on 24 Apr 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

GNU Mailman 2.x before 2.1.30 uses the .obj extension for scrubbed application/octet-stream MIME parts. This behavior may contribute to XSS attacks against list-archive visitors, because an HTTP reply from an archive web server may lack a MIME type, and a web browser may perform MIME sniffing, conclude that the MIME type should have been text/html, and execute JavaScript code.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2020-12137?

It affects 6 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mailman` | Red Hat:enterprise_linux:8::appstream | All versions | 3:2.1.29-10.module+el8.3.0+6860+8e47d84b |
| `mailman-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 3:2.1.29-10.module+el8.3.0+6860+8e47d84b |
| `mailman-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 3:2.1.29-10.module+el8.3.0+6860+8e47d84b |
| `mailman` | SUSE:Linux Enterprise Point of Sale 11 SP3 | All versions | 2.1.15-9.6.20.1 |
| `mailman` | SUSE:Linux Enterprise Server 11 SP4-LTSS | All versions | 2.1.15-9.6.20.1 |

Products: Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Gnu Mailman, Opensuse Backports Sle, Opensuse Leap.

## How do I fix CVE-2020-12137?

Upgrade to a fixed version.

## Is CVE-2020-12137 being exploited?

There is no known exploitation of CVE-2020-12137 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-12137 and fix it if it is affected.

What it is: CVE-2020-12137 is a medium-severity cross-site scripting vulnerability in Canonical Ubuntu Linux, published on 24 Apr 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-2020-12137 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. 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-2020-12137/ (Markdown: https://insights.sbomify.com/CVE-2020-12137/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-12137
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-12137
- OSV: https://osv.dev/vulnerability/CVE-2020-12137

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-12137/
Summaries are generated and may contain mistakes; the official description above is the record.