CVE-2021-31408: Vaadin Flow

High severity, CVSS 7.1. EPSS: 0.3% chance of exploitation in the next 30 days.

Authentication.logout() helper in com.vaadin:flow-client versions 5.0.0 prior to 6.0.0 (Vaadin 18), and 6.0.0 through 6.0.4 (Vaadin 19.0.0 through 19.0.3) uses incorrect HTTP method, which, in combination with Spring Security CSRF protection, allows local attackers to access Fusion endpoints after the user attempted to log out.

Affected products

• Vaadin Flow: from 5.0.0, before 6.0.0 (fixed in 6.0.0); from 6.0.0, before 6.0.5 (fixed in 6.0.5)
• Vaadin Vaadin: from 19.0.0, before 19.0.4 (fixed in 19.0.4); version 18.0.0 only

Published 2021-04-23. Last modified 2026-06-17.