# CVE-2026-110803: Vaadin Framework 8 session lock denial of service

Source: https://junglewise.ai/threats/cve-2026-110803-vaadinservice-requestend-in-vaadin-framework-8-locks-the-session  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-21. Updated: 2026-10-21  
License: CC BY 4.0 with a link back

CVE-2026-110803 · Severity: info · Published 2026-10-21

Vaadin Framework 8 is a Java web application framework. An attacker can supply a malformed request parameter that causes the framework to lock a user session and fail to release it, blocking all subsequent requests from that user and exhausting the application's thread pool. Any attacker without authentication can repeat this attack by obtaining a session cookie from a single initial request, eventually taking the entire application offline.

Vendors: [Vaadin](https://junglewise.ai/threats/vendors/vaadin).

## Quick answers

**Is CVE-2026-110803 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-110803 being exploited in the wild.

**How severe is CVE-2026-110803?** Informational severity, published 21 October 2026.

**Which products and versions are affected?** Vaadin Framework 8.16.0 to 8.32.1.

**Is there a fix for CVE-2026-110803?** Yes: fixed in 8.32.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-110803 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-110803?** Check whether you run Vaadin Framework at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 8.32.2

## Technical details

VaadinService.requestEnd() holds a session lock while reading the v-uiId request parameter; if the parameter is non-numeric, Integer.parseInt throws an exception within the locked section, preventing the lock from being released in a finally block. Subsequent requests to the same session block indefinitely waiting to acquire the lock, and repeated attacks exhaust the container's thread pool. The attack requires only network access and a valid session cookie; no user interaction or elevated privileges are needed.

## Affected products

- Vaadin Framework 8.16.0 to 8.32.1

## Timeline

- 2026-10-21: disclosed

## References

- [https://repo.maven.apache.org/maven2](https://repo.maven.apache.org/maven2)
- [https://github.com/vaadin/framework/releases/tag/8.32.2](https://github.com/vaadin/framework/releases/tag/8.32.2)

## Related threats

- [Vaadin server push CORS header injection](https://junglewise.ai/threats/cve-2026-110737-the-push-endpoint-of-a-vaadin-application-that-uses-server-push)