# CVE-2021-42009: Apache Traffic Control Traffic Ops Email Injection Vulnerability

> Authenticated users can inject arbitrary email bodies and recipients via crafted requests, enabling spam or phishing from the server.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Oct 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-gw97-f6h8-gm94, GO-2022-0602

## What is CVE-2021-42009?

CVE-2021-42009 is a medium-severity vulnerability in Apache Traffic Control, published on 12 Oct 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

An authenticated Apache Traffic Control Traffic Ops user with Portal-level privileges can send a request with a specially-crafted email subject to the /deliveryservices/request Traffic Ops endpoint to send an email, from the Traffic Ops server, with an arbitrary body to an arbitrary email address. Apache Traffic Control 5.1.x users should upgrade to 5.1.3 or 6.0.0. 4.1.x users should upgrade to 5.1.3.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-42009?

3 open source packages ship an affected version, including github.com/apache/trafficcontrol. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/apache/trafficcontrol` | Go | All versions | 5.1.3 |
| `github.com/apache/trafficcontrol` | Go | All versions | 5.1.3 |
| `github.com/apache/trafficcontrol` | Go | All versions | 5.1.3+incompatible |

Products: Apache Traffic Control.

## How do I fix CVE-2021-42009?

Upgrade github.com/apache/trafficcontrol to a fixed version for your release line: 5.1.3 or 5.1.3+incompatible.

## Is CVE-2021-42009 being exploited?

There is no known exploitation of CVE-2021-42009 in the wild and no public exploit code.

## Other vulnerabilities in Apache Traffic Control

- [CVE-2024-45387](https://insights.sbomify.com/CVE-2024-45387/): Apache Traffic Control: SQL Injection in Traffic Ops endpoint PUT deliveryservice_request_comments (critical 9.9)
- [CVE-2021-43350](https://insights.sbomify.com/CVE-2021-43350/): LDAP filter injection vulnerability in Traffic Ops (critical 9.8)
- [CVE-2019-12405](https://insights.sbomify.com/CVE-2019-12405/): Improper Authentication in Apache Traffic Control (critical 9.8)
- [CVE-2025-61581](https://insights.sbomify.com/CVE-2025-61581/): Apache Traffic Control: ReDoS issue in Traffic Router configuration (high 7.5)
- [CVE-2022-23206](https://insights.sbomify.com/CVE-2022-23206/): Server-Side Request Forgery in Traffic Ops endpoint POST /user/login/oauth (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-42009 and fix it if it is affected.

What it is: CVE-2021-42009 is a medium-severity vulnerability in Apache Traffic Control, published on 12 Oct 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-42009 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/apache/trafficcontrol (Go): affected all versions; fixed in 5.1.3
- github.com/apache/trafficcontrol (Go): affected all versions; fixed in 5.1.3
- github.com/apache/trafficcontrol (Go): affected all versions; fixed in 5.1.3+incompatible

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-2021-42009/ (Markdown: https://insights.sbomify.com/CVE-2021-42009/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-42009
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-42009
- OSV: https://osv.dev/vulnerability/CVE-2021-42009

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-42009/
Summaries are generated and may contain mistakes; the official description above is the record.