CVE-2021-33611Network attack vector

Browser script execution via unsanitized theme parameter

Published Nov 2, 2021 · Updated Sep 17, 2024

Reflected XSS in Vaadin Menu Bar 1.0.0 through 1.2.0 allows remote attackers to run JavaScript when a victim opens a crafted URL. The test/visual/theme.html source reads the theme query parameter without validation and inserts it into a document.write-generated HTML import. The vulnerable resource must be exposed through a webjar in a Vaadin 14.0.0 through 14.4.4 application, and exploitation requires a victim to open the link.

CVSS severity6.1
Medium
EPSS probability0.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Vaadin Menu Bar 1.0.0 through 1.2.0 allows remote attackers to run JavaScript when a victim opens a crafted URL. The test/visual/theme.html source reads the theme query parameter without validation and inserts it into a document.write-generated HTML import. The vulnerable resource must be exposed through a webjar in a Vaadin 14.0.0 through 14.4.4 application, and exploitation requires a victim to open the link.

The record

CVE
CVE-2021-33611
Published
Nov 2, 2021
Updated
Sep 17, 2024
Vendor
Vaadin
Product
Vaadin Menu Bar
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.0 <unspecified
  2. Affected versionversion=unspecified <=1.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Vaadin · Vaadin Menu Barversion=1.0.0 <unspecified; version=unspecified <=1.2.0
Vaadin · Vaadin Frameworkversion=14.0.0 <unspecified; version=unspecified <=14.4.4

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1Vaadin Ltd.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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