What is CVE-2021-33611?

CVE-2021-33611 is a medium-severity vulnerability in Vaadin, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-11-02.

How severe is CVE-2021-33611?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Vaadin

CVE-2021-33611

Missing output sanitization in test sources in org.webjars.bowergithub.vaadin:vaadin-menu-bar versions 1.0.0 through 1.2.0 (Vaadin 14.0.0 through 14.4.4) allows remote attackers to execute malicious JavaScript in browser by opening crafted URL

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-11-02 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.010 (60.9th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 60.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000

Affected products

Vaadin — versions 14.0.0, unspecified
Vaadin Vaadin-Menu-Bar — versions 1.0.0, unspecified

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

vaadin.com/security/cve-2021-33611 (Exploit, Third Party Advisory)
github.com/vaadin/vaadin-menu-bar/pull/126 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-33611?: CVE-2021-33611 is a medium-severity vulnerability in Vaadin, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-11-02.
How severe is CVE-2021-33611?: Medium severity. CVSS v3 base score is 6.1 out of 10.