---
cve: "CVE-2021-31406"
severity: "MEDIUM"
cvss: 4.0
epss: "0.2%"
vendor: "Vaadin"
kev: false
exploited: false
published: "2021-04-23 16:05:41"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-21T10:59:09+02:00"
---

# CVE-2021-31406

> 4.0 MEDIUM · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Gering | warn |
| I Integrität | Gering | warn |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- b9cc454b011a504d841b53d192cf21f45a0bf829 (Commit)
- 8c0a5c1db4c289feb4c766381ed9e3fe637815db (Commit)

## Referenzen

- <https://vaadin.com/security/cve-2021-31406>
- <https://github.com/vaadin/flow/pull/10157>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2021-31406) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_