CVE-2026-110803 vaadin CVE debrief

Who should care

Defenders and administrators of systems using Vaadin Framework 8 should be aware of this vulnerability and take necessary actions to prevent potential denial-of-service attacks. This includes upgrading to version 8.32.2 or applying the provided mitigation.

Why it matters

Defenders should prioritize addressing CVE-2026-110803 due to the potential for denial-of-service attacks on Vaadin Framework 8 systems. Upgrading to version 8.32.2 or applying the mitigation is crucial to prevent application downtime and thread pool exhaustion.

• Denial of service due to session lock leak
• Potential exhaustion of thread pool
• Application downtime due to repeated requests with invalid UI ID

Technical summary

The vulnerability in Vaadin Framework 8 arises from the way VaadinService.requestEnd() handles the session lock and reads the v-uiId request parameter. When a non-numeric v-uiId is provided, the session lock is never released, leading to a denial-of-service condition. This issue is fixed in Vaadin Framework 8.32.2. A session cookie obtained with a single request is sufficient for exploitation, and no authentication is required. The vulnerability can cause every later request to that session to block indefinitely in VaadinService.lockSession(), potentially exhausting the thread pool and leading to application downtime.

Defensive priority

Defenders should prioritize upgrading to Vaadin Framework 8.32.2 or later, or applying the provided mitigation, to prevent potential denial-of-service attacks. This is particularly important for systems using Vaadin Framework 8, as Vaadin 10 and later, as well as Vaadin Framework 7, are not affected by this issue.

Recommended defensive actions

• Confirm whether affected Vaadin Framework 8 product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates to Vaadin Framework 8.32.2 or later through normal change control where exposure is confirmed.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Perform an inventory of systems using Vaadin Framework 8 to prioritize remediation efforts.

Evidence notes

The CVE record and source item provide detailed information about the vulnerability, including its description, affected versions, and fixed versions. The vendor, Vaadin, has also provided references to their security page and a GitHub release tag for version 8.32.2.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.