What is the CVSS score of CVE-2021-33604?

CVE-2021-33604 has a CVSS 3.1 base score of 2.5 (Low). CVSS vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N. EPSS exploitation probability: 0.3%.

Is there a patch available for CVE-2021-33604?

Yes, a patch is available for CVE-2021-33604. Update the affected software to the latest version immediately.

Vaadin CVE-2021-33604

LOW

Encoding Error (CWE-172)

2021-06-24 security@vaadin.com

RCE Vaadin Flow Server

2.5

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-172
Impact	CVSS score of 2.5 (LOW). Attack characteristics: local attack vector, high complexity, no privileges required, user interaction required.
Exploit ScenarioDerived	Successful exploitation could compromise the low-severity affected system.

Monitor Track and reassess. Why: LOW severity (CVSS 0.1-3.9).

Patch available 0.3% exploitation probability (EPSS)

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AnalysisAI

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. Rated low severity (CVSS 2.5), this vulnerability is no authentication required.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affected Packages

maven com.vaadin:vaadin-bom fix: 14.6.2, 19.0.9

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in maven

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-172. 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. Affected products include: Vaadin Flow-Server, Vaadin. Version information: through 2.6.1.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 2.5 LOW

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Local

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

DescriptionNVD

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.

Threat Intelligence Overview

EPSS Score

0.3%

Top 80% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity LOW

CISA KEV No

Public POC No

EPSS 0.3%

Patch available Yes

Active threat No

Deciding rule

LOW severity (CVSS 0.1-3.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Defer

Exploitation· derived

None

System Exposure· derived

Small

Automatable· derived

Human Impact· derived

Low

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +12

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Remote Code Execution CRITICAL

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

Affected Products (CPE)NVD

cpe:2.3:a:vaadin:flow-server:*:*:*:*:*:*:*:*

cpe:2.3:a:vaadin:vaadin:*:*:*:*:*:*:*:*

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References

Advisories & patches

PATCH https://github.com/vaadin/flow/pull/11099 ADVISORY https://vaadin.com/security/cve-2021-33604

Search Externally

GitHub PoC

Exploit-DB PacketStorm Snyk Rapid7 Nuclei Templates Trickest PoC

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