# CVE-2020-36320: Regular expression Denial of Service (ReDoS) in EmailValidator class in Vaadin 7

> Attackers can cause denial of service in Vaadin applications by submitting malicious email addresses that trigger excessive resource consumption in the EmailValidator.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Apr 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-42j4-733x-5vcf

## What is CVE-2020-36320?

CVE-2020-36320 is a high-severity denial of service vulnerability in Vaadin, published on 23 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Unsafe validation RegEx in EmailValidator class in com.vaadin:vaadin-server versions 7.0.0 through 7.7.21 (Vaadin 7.0.0 through 7.7.21) allows attackers to cause uncontrolled resource consumption by submitting malicious email addresses.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2020-36320?

4 open source packages ship an affected version, including com.vaadin:vaadin-bom and com.vaadin:vaadin-server. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `com.vaadin:vaadin-bom` | Maven | From 7.0.0.beta1 | 7.7.22 |
| `com.vaadin:vaadin-bom` | Maven | From 7.0.0.beta1 | 7.7.22 |
| `com.vaadin:vaadin-server` | Maven | From 7.0.0.beta1 | 7.7.22 |
| `com.vaadin:vaadin-server` | Maven | From 7.0.0.beta1 | 7.7.22 |

Products: Vaadin Vaadin.

## How do I fix CVE-2020-36320?

Upgrade com.vaadin:vaadin-bom to 7.7.22 or later.

## Is CVE-2020-36320 being exploited?

There is no known exploitation of CVE-2020-36320 in the wild and no public exploit code.

## Other vulnerabilities in Vaadin

- [CVE-2021-31409](https://insights.sbomify.com/CVE-2021-31409/): Server session is not invalidated when logout() helper method of Authentication module is used in Vaadin 18-19 (high 7.5)
- [CVE-2021-33611](https://insights.sbomify.com/CVE-2021-33611/): Reflected cross-site scripting in vaadin-menu-bar webjar resources in Vaadin 14 (medium 6.1)
- [CVE-2023-25499](https://insights.sbomify.com/CVE-2023-25499/): Possible information disclosure in non visible components (medium 5.7)
- [CVE-2022-29567](https://insights.sbomify.com/CVE-2022-29567/): Possible information disclosure inside TreeGrid component with default data provider (medium 5.7)
- [CVE-2019-25028](https://insights.sbomify.com/CVE-2019-25028/): Stored cross-site scripting in Grid component in Vaadin 7 and 8 (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-36320 and fix it if it is affected.

What it is: CVE-2020-36320 is a high-severity denial of service vulnerability in Vaadin, published on 23 Apr 2021. 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-2020-36320 in the wild and no public exploit code.

Affected packages and fixed versions:
- com.vaadin:vaadin-bom (Maven): affected from 7.0.0.beta1; fixed in 7.7.22
- com.vaadin:vaadin-bom (Maven): affected from 7.0.0.beta1; fixed in 7.7.22
- com.vaadin:vaadin-server (Maven): affected from 7.0.0.beta1; fixed in 7.7.22
- com.vaadin:vaadin-server (Maven): affected from 7.0.0.beta1; fixed in 7.7.22

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-2020-36320/ (Markdown: https://insights.sbomify.com/CVE-2020-36320/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-36320
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-36320
- OSV: https://osv.dev/vulnerability/CVE-2020-36320

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-36320/
Summaries are generated and may contain mistakes; the official description above is the record.