Is CVE-2021-31406 in the CISA KEV catalog?

No. CVE-2021-31406 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-31406?

CVE-2021-31406 has a CVSS v3 base score of 4.0 (MEDIUM).

What is the EPSS score for CVE-2021-31406?

CVE-2021-31406 has an EPSS score of 0.21% (11th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-31406?

Upgrade flow to 5.0.4 or later. Fixes are available for 2 affected products.

CVE & CISA-KEV Catalog

CVE-2021-31406

MEDIUM

4.0

CVSS v3

NVD

Description

Non-constant-time comparison of CSRF tokens in endpoint request handler in com.vaadin:flow-server versions 3.0.0 through 5.0.3 (Vaadin 15.0.0 through 18.0.6), and com.vaadin:fusion-endpoint version 6.0.0 (Vaadin 19.0.0) allows attacker to guess a security token for Fusion endpoints via timing attack.

CWE-208 CWE-203

How to fix

Remediation Available

flowNVD

Affected:>= 3.0.0, < 5.0.4Fixed in:5.0.4CVE-2021-31406derived from NVD

vaadinNVD

Affected:>= 15.0.0, < 18.0.7Fixed in:18.0.7CVE-2021-31406derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.21%probability of exploitation in 30 days

11thpercentile

Low risk: more likely to be exploited than 11% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

vaadin.com

Related Vulnerabilities

Other CWE-208 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2019-9494	Medium	5.9	3.7%	-	Fix
CVE-2019-16782	Medium	6.3	3.7%	-	Fix
CVE-2025-53940	Unscored	-	2.6%	-	-
CVE-2020-1926	Medium	5.9	2.5%	-	Fix
CVE-2021-43298	Critical	9.8	2.3%	-	Fix
CVE-2024-29995	High	8.1	1.5%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.