CVE-2026-83594 Apache Software Foundation CVE debrief

Who should care

Defenders and administrators of Apache Wicket applications should assess exposure and prioritize remediation. The vulnerability can be exploited by a client that can load the page without requiring authentication or user interaction, making it a high-severity issue.

Why it matters

CVE-2026-83594 is a high-severity vulnerability in Apache Wicket that can lead to a denial-of-service (DoS) attack. Defenders and administrators of Apache Wicket applications should assess exposure and prioritize remediation.

• Potential for denial-of-service (DoS) attacks
• Exploitation requires only loading the page, no authentication or user interaction needed
• Heap memory exhaustion possible with large client-supplied size values
• Remediation priority: upgrade to fixed version or restrict access to affected component

Technical summary

The vulnerability is caused by the FileUploadToResourceField component in Apache Wicket, which allows a client to specify the size of a file upload. The component allocates a byte array based on the client-supplied size, which can lead to a large memory allocation. The issue is exacerbated by the fact that the callback URL is rendered into the page and can be accessed by any client that can load the page.

Defensive priority

High

Recommended defensive actions

• Upgrade to version 9.25.0 or 10.12.0, which fix the issue
• Review and update affected applications to use a fixed version of Apache Wicket
• Monitor and restrict access to the affected component
• Confirm whether affected 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 or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The vulnerability is caused by the FileUploadToResourceField component in Apache Wicket, which allows a client to specify the size of a file upload. The component allocates a byte array based on the client-supplied size, which can lead to a large memory allocation. The issue is exacerbated by the fact that the callback URL is rendered into the page and can be accessed by any client that can load the page.

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.