CVE-2026-84170 Apache Software Foundation CVE debrief

Who should care

Defenders responsible for Apache Wicket applications, especially those using FileUploadToResourceField or mounting FileUploadResourceReference, should assess exposure and prioritize patching or mitigation.

Why it matters

CVE-2026-84170 is a high-severity vulnerability in Apache Wicket that allows for form-less file uploads with inadequate limits, potentially leading to denial-of-service. Defenders should prioritize patching or mitigating this vulnerability, especially in environments where untrusted users can submit file uploads. The vulnerability affects Wicket versions 9.14.0 through 9.24.0 and 10.0.0 through 10.9.1, and users are recommended to upgrade to version 9.25.0 or 10.12.0.

• Potential for denial-of-service due to excessive resource consumption
• Need for verification of affected versions and exposure
• Priority for patching or mitigating vulnerable instances
• Potential for monitoring and limiting upload activity

Technical summary

The vulnerability lies in org.apache.wicket.markup.html.form.upload.resource.AbstractFileUploadResource, which handles form-less file uploads. The resource is an application-wide singleton with no component to consult, so it takes limits from request parameters maxSize, fileMaxSize, and fileCountMax. However, these limits can be easily bypassed by a malicious client, allowing for excessive resource consumption.

Defensive priority

Defenders should prioritize patching or mitigating this vulnerability, especially in environments where untrusted users can submit file uploads.

Recommended defensive actions

• Patch to version 9.25.0 or 10.12.0
• Review and limit upload resource usage
• Monitor for suspicious upload activity
• Verify affected Wicket versions in use
• Check for exposure in environments where untrusted users can submit file uploads
• Review compensating controls for exposed systems
• Track exceptions and retest remediated assets

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, affected versions, and recommended fixes. The vulnerability lies in org.apache.wicket.markup.html.form.upload.resource.AbstractFileUploadResource, which handles form-less file uploads. The resource is an application-wide singleton with no component to consult, so it takes limits from request parameters maxSize, fileMaxSize, and fileCountMax. However, these limits can be easily bypassed by a malicious client, allowing for excessive resource.

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.