CVE-2021-33604

Name: CVE-2021-33604
Creator: NVD / NIST
Published: 2021-06-24T12:15:08.157+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

LOWCVSS 2.5/10EPSS 0.29%

Last modified Jun 17, 2026

CVE-2021-33604 is a low-severity vulnerability rated 2.5/10 on the CVSS scale. URL encoding error in development mode handler in com.vaadin:flow-server versions 2.0.0 through 2.6.1 (Vaadin 14.0.0 through 14.6.1), 3.0.0 through 6.0.9 (Vaadin 15.0.0 through 19.0.8) allows local user to execute arbitrary JavaScript code by opening crafted URL in browser.. EPSS estimates a 0.29% chance of exploitation in the next 30 days.

Description

URL encoding error in development mode handler in com.vaadin:flow-server versions 2.0.0 through 2.6.1 (Vaadin 14.0.0 through 14.6.1), 3.0.0 through 6.0.9 (Vaadin 15.0.0 through 19.0.8) allows local user to execute arbitrary JavaScript code by opening crafted URL in browser.

Metrics

CVSS 3.1

2.5/10

CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N

EPSS Probability

0.29%

20.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-172

Affected Software

Vendor	Product	Versions
Vaadin	Flow-Server	>= 2.0.0, <= 2.6.1
Vaadin	Flow-Server	>= 3.0.0, <= 5.0.0
Vaadin	Flow-Server	>= 6.0.0, <= 6.0.9
Vaadin	Vaadin	>= 14.0.0, <= 14.6.1
Vaadin	Vaadin	>= 15.0.0, <= 18.0.0
Vaadin	Vaadin	>= 19.0.0, <= 19.0.8

References

https://github.com/vaadin/flow/pull/11099Patch, Third Party Advisory
https://vaadin.com/security/cve-2021-33604Vendor Advisory
https://github.com/vaadin/flow/pull/11099Patch, Third Party Advisory
https://vaadin.com/security/cve-2021-33604Vendor Advisory

Timeline

Published: Jun 24, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-33604?

How severe is CVE-2021-33604?

CVE-2021-33604 has a CVSS score of 2.5/10 (LOW severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.

How do I fix CVE-2021-33604?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-33604?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST