# CVE-2020-2253: Missing hostname validation in Email Extension Plugin

> Jenkins Email Extension Plugin fails to validate SMTP server hostnames, allowing potential man-in-the-middle attacks or server-side request forgery.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-4qrj-99r6-jfrh

## What is CVE-2020-2253?

CVE-2020-2253 is a medium-severity server-side request forgery vulnerability in Jenkins Email Extension Plugin, published on 16 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Jenkins Email Extension Plugin 2.75 and earlier does not perform hostname validation when connecting to the configured SMTP server.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2020-2253?

2 open source packages ship an affected version, including org.jenkins-ci.plugins:email-ext. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.jenkins-ci.plugins:email-ext` | Maven | All versions | 2.76 |
| `org.jenkins-ci.plugins:email-ext` | Maven | All versions | 2.76 |

Products: Jenkins Email Extension.

## How do I fix CVE-2020-2253?

Upgrade org.jenkins-ci.plugins:email-ext to 2.76 or later.

## Is CVE-2020-2253 being exploited?

There is no known exploitation of CVE-2020-2253 in the wild and no public exploit code.

## Other vulnerabilities in Jenkins Email Extension Plugin

- [CVE-2023-25765](https://insights.sbomify.com/CVE-2023-25765/): Sandbox escape in Jenkins Email Extension Plugin (critical 9.9)
- [CVE-2019-1003032](https://insights.sbomify.com/CVE-2019-1003032/): Script security sandbox bypass in Jenkins Email Extension Plugin (critical 9.9)
- [CVE-2026-48920](https://insights.sbomify.com/CVE-2026-48920/): Jenkins Email Extension Plugin: Attackers able to control email content may specify `file:` URLs for images to read arbitrary files from Jenkins controller filesystem (high 8.8)
- [CVE-2020-2232](https://insights.sbomify.com/CVE-2020-2232/): Jenkins Email Extension Plugin SMTP password transmitted and displayed in plain text (high 7.5)
- [CVE-2018-1000176](https://insights.sbomify.com/CVE-2018-1000176/): Jenkins Email Extension Plugin showed plain text SMTP password in configuration form field (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-2253 and fix it if it is affected.

What it is: CVE-2020-2253 is a medium-severity server-side request forgery vulnerability in Jenkins Email Extension Plugin, published on 16 Sep 2020. 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-2020-2253 in the wild and no public exploit code.

Affected packages and fixed versions:
- org.jenkins-ci.plugins:email-ext (Maven): affected all versions; fixed in 2.76
- org.jenkins-ci.plugins:email-ext (Maven): affected all versions; fixed in 2.76

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-2020-2253/ (Markdown: https://insights.sbomify.com/CVE-2020-2253/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-2253
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-2253
- OSV: https://osv.dev/vulnerability/CVE-2020-2253

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-2253/
Summaries are generated and may contain mistakes; the official description above is the record.