What is the CVSS score of CVE-2021-31404?

CVE-2021-31404 has a CVSS 3.1 base score of 2.5 (Low). CVSS vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N. EPSS exploitation probability: 0.2%.

Is there a patch available for CVE-2021-31404?

Yes, a patch is available for CVE-2021-31404. Update the affected software to the latest version immediately.

Vaadin CVE-2021-31404

LOW

Observable Timing Discrepancy (CWE-208)

2021-04-23 security@vaadin.com

CSRF Flow Vaadin

2.5

CVSS 3.1 · NVD

View

Vulnerability Assessment

Weakness	CWE CWE-208 ASVS 5.0 V6 - Authentication Timing attack prevention
Impact	CVSS score of 2.5 (LOW). Attack characteristics: local attack vector, high complexity, low privileges required, no user interaction not 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 0.2% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAI

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:flow-server fix: 1.0.14, 2.4.7, 5.0.3

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-208. Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 prior to 14), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack. Affected products include: Vaadin Flow, Vaadin. Version information: through 1.0.13.

Know when Vaadin gets its next vulnerability

Watch products and get an email when something new is published
Check this CVE against your own stack and servers
Exploit and PoC references, threat intelligence from 22 sources

Continue with Google Continue with GitHub

No credit card · 7-day full trial

Severity by source

NVD PRIMARY 2.5 LOW

AV:L/AC:H/PR:L/UI:N/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

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

DescriptionNVD

Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 prior to 14), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.

Threat Intelligence Overview

EPSS Score

0.2%

Top 89% 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 0.2%

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

Cross-Site Request Forgery MEDIUM

Cross-Site Request Forgery exploits the automatic credential inclusion behavior of web browsers.

Affected Products (CPE)NVD

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

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

More in Vaadin

View all

CVE-2021-33611 MEDIUM This Month POC

6.1 Nov 02

Missing output sanitization in test sources in org.webjars.bowergithub.vaadin:vaadin-menu-bar versions 1.0.0 through 1.2

CVE-2026-110803 HIGH This Week

8.7 Oct 21

Unauthenticated remote denial of service in Vaadin Framework 8 (com.vaadin:vaadin-server 8.16.0 through 8.32.1, and vaad

CVE-2026-107588 HIGH This Week

8.4 Oct 21

Charts rendered by Vaadin Charts across Vaadin 22 through 25.3.0 bundle a pinned Highcharts release (9.2.2 in Vaadin 22-

CVE-2021-31411 HIGH This Week

7.8 May 05

Insecure temporary directory usage in frontend build functionality of com.vaadin:flow-server versions 2.0.9 through 2.5.

CVE-2022-29567 HIGH This Week

7.5 May 24

The default configuration of a TreeGrid component uses Object::toString as a key on the client-side and server communica

CVE-2021-31409 HIGH This Week

7.5 May 06

Unsafe validation RegEx in EmailValidator component in com.vaadin:vaadin-compatibility-server versions 8.0.0 through 8.1

CVE-2021-31410 HIGH This Week

7.5 Apr 23

Overly relaxed configuration of frontend resources server in Vaadin Designer versions 4.3.0 through 4.6.3 allows remote

CVE-2021-31407 HIGH This Week

7.5 Apr 23

Vulnerability in OSGi integration in com.vaadin:flow-server versions 1.2.0 through 2.4.7 (Vaadin 12.0.0 through 14.4.9),

CVE-2021-31405 HIGH This Week

7.5 Apr 23

Unsafe validation RegEx in EmailField component in com.vaadin:vaadin-text-field-flow versions 2.0.4 through 2.3.2 (Vaadi

CVE-2021-31408 HIGH This Week

7.1 Apr 23

Authentication.logout() helper in com.vaadin:flow-client versions 5.0.0 prior to 6.0.0 (Vaadin 18), and 6.0.0 through 6.

CVE-2023-25499 MEDIUM This Month

6.5 Jun 22

When adding non-visible components to the UI in server side, content is sent to the browser in Vaadin 10.0.0 through 10.

CVE-2026-91860 MEDIUM This Month

6.3 Sep 30

Deep-merge prototype pollution in Vaadin Charts and Vaadin Component Base lets remote, unauthenticated attackers write a

Same weakness CWE-208 – Observable Timing Discrepancy

View all

CVE-2026-23519 CRITICAL POC

9.8

CVE-2024-47178 HIGH POC

8.7

CVE-2026-69247 HIGH POC

8.2

CVE-2026-54736 HIGH POC

8.2

CVE-2025-68621 HIGH POC

7.4

CVE-2026-77582 MEDIUM POC

6.9

CVE-2026-88010 MEDIUM POC

6.3

CVE-2024-54772 MEDIUM POC

5.4

Same technique CSRF

View all

CVE-2016-6277 HIGH POC

8.8

CVE-2014-100005 HIGH POC

8.0

CVE-2017-9757 HIGH POC

8.8

CVE-2013-5696 MEDIUM POC

6.8

CVE-2013-4152 MEDIUM POC

6.8

CVE-2024-7094 CRITICAL

9.8

CVE-2015-4624 HIGH POC

7.5

CVE-2020-36836 HIGH POC

8.0

References

Advisories & patches

PATCH https://github.com/vaadin/flow/pull/9875 ADVISORY https://vaadin.com/security/cve-2021-31404

Search Externally

GitHub PoC

Exploit-DB PacketStorm Snyk Rapid7 Nuclei Templates Trickest PoC

Back