# CVE-2021-33609: Denial of service in DataCommunicator class in Vaadin 8

Source: https://junglewise.ai/threats/cve-2021-33609-denial-of-service-in-datacommunicator-class-in-vaadin-8  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-10-13  
License: CC BY 4.0 with a link back

CVE-2021-33609 · Severity: low · CVSS 3.1 · Published 2021-10-13

Denial of service in DataCommunicator class in Vaadin 8

Technologies: [com.vaadin:vaadin-server (Maven)](https://junglewise.ai/threats/technologies/com-vaadin-vaadin-server). Vendors: [Maven](https://junglewise.ai/threats/vendors/maven).

## Quick answers

**Is CVE-2021-33609 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-33609 being exploited in the wild.

**How severe is CVE-2021-33609?** Low severity, with a CVSS score of 3.1, published 13 October 2021.

**Which products and versions are affected?** com.vaadin:vaadin-server (Maven) ECOSYSTEM:introduced=8.0.6,fixed=8.14.1.

**Is there a fix for CVE-2021-33609?** Yes. com.vaadin:vaadin-server (Maven): upgrade to 8.14.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2021-33609?** Check whether you run com.vaadin:vaadin-server (Maven) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- com.vaadin:vaadin-server (Maven): upgrade to 8.14.1 or later

  ```sh
  # set com.vaadin:vaadin-server to 8.14.1 in your pom.xml or build.gradle
  ```


## Affected products

- com.vaadin:vaadin-server (Maven) ECOSYSTEM:introduced=8.0.6,fixed=8.14.1

## Identifiers

- CVE-2021-33609
- GHSA-qcgx-crrx-38v5

## Related threats

- [Vaadin vulnerable to Cross-site Scripting](https://junglewise.ai/threats/cve-2025-15022-vaadin-vulnerable-to-cross-site-scripting)
- [Vaadin Framework possible file bypass via upload validation on the server-side](https://junglewise.ai/threats/cve-2025-9467-vaadin-framework-possible-file-bypass-via-upload-validation-on-the)
- [Denial of service in DataCommunicator class in Vaadin 8](https://junglewise.ai/threats/denial-of-service-in-datacommunicator-class-in-vaadin-8-c2dd912d)
- [Timing side channel vulnerability in UIDL request handler in Vaadin 7 and 8](https://junglewise.ai/threats/cve-2021-31403-timing-side-channel-vulnerability-in-uidl-request-handler-in)
- [Stored cross-site scripting in Grid component in Vaadin 7 and 8](https://junglewise.ai/threats/cve-2019-25028-stored-cross-site-scripting-in-grid-component-in-vaadin-7-and-8)