# CVE-2021-31408: Server session is not invalidated when logout() helper method of Authentication module is used in Vaadin 18-19

> Local attackers can access protected endpoints after logout due to incorrect HTTP method usage in Vaadin's authentication module when CSRF protection is enabled.

- **Severity:** Medium 6.3 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 23 Apr 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-mr8h-j9cv-4m8h

## What is CVE-2021-31408?

CVE-2021-31408 is a medium-severity authentication bypass vulnerability in Vaadin, published on 23 Apr 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

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.

Weakness: CWE-613 (DEPRECATED: Insufficient Session Expiration)

## Which versions are affected by CVE-2021-31408?

2 open source packages ship an affected version, including com.vaadin:vaadin-bom. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `com.vaadin:vaadin-bom` | Maven | From 18.0.0 | 19.0.4 |
| `com.vaadin:vaadin-bom` | Maven | From 18.0.0 | 19.0.4 |

Products: Vaadin Flow, Vaadin Vaadin.

## How do I fix CVE-2021-31408?

Upgrade com.vaadin:vaadin-bom to 19.0.4 or later.

## Is CVE-2021-31408 being exploited?

There is no known exploitation of CVE-2021-31408 in the wild and no public exploit code.

## Other vulnerabilities in Vaadin

- [CVE-2021-31407](https://insights.sbomify.com/CVE-2021-31407/): Server classes and resources exposure in OSGi applications using Vaadin 12-14 and 19 (high 8.6)
- [CVE-2021-31405](https://insights.sbomify.com/CVE-2021-31405/): Regular expression denial of service (ReDoS) in EmailField component in Vaadin 14 and 15-17 (high 7.5)
- [CVE-2021-31411](https://insights.sbomify.com/CVE-2021-31411/): Insecure temporary directory usage in frontend build functionality of Vaadin 14 and 15-19 (medium 6.3)
- [CVE-2019-25027](https://insights.sbomify.com/CVE-2019-25027/): Reflected cross-site scripting in default RouteNotFoundError view in Vaadin 10 and 11-13 (medium 6.1)
- [CVE-2020-36321](https://insights.sbomify.com/CVE-2020-36321/): Directory traversal in development mode handler in Vaadin 14 and 15-17 (medium 5.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-31408 and fix it if it is affected.

What it is: CVE-2021-31408 is a medium-severity authentication bypass vulnerability in Vaadin, published on 23 Apr 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-31408 in the wild and no public exploit code.

Affected packages and fixed versions:
- com.vaadin:vaadin-bom (Maven): affected from 18.0.0; fixed in 19.0.4
- com.vaadin:vaadin-bom (Maven): affected from 18.0.0; fixed in 19.0.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-31408/ (Markdown: https://insights.sbomify.com/CVE-2021-31408/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31408
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31408
- OSV: https://osv.dev/vulnerability/CVE-2021-31408

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-31408/
Summaries are generated and may contain mistakes; the official description above is the record.