CVE-2026-93363

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Improper Access Control in PayloadCMS Vercel Blob Storage Adapter

Publication date: 2026-09-25

Last updated on: 2026-09-30

Assigner: VulnCheck

Description

The @payloadcms/storage-vercel-blob storage adapter for Payload contains an improper access control vulnerability that allows authenticated users to bypass collection-level permissions by accessing the client-upload route directly. Attackers can upload files through the client-upload endpoint without possessing the required collection access permissions, circumventing the intended access control enforcement.

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Meta Information

Published

2026-09-25

Last Modified

2026-09-30

Generated

2026-10-16

AI Q&A

2026-09-25

EPSS Evaluated

2026-10-14

NVD

CVE-2026-93363

EUVD

EUVD-2026-87206

Affected Vendors & Products

Vendor	Product	Version / Range
payloadcms	storage-vercel-blob	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-862	The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

Attack-Flow Graph

Executive Summary

This vulnerability is an improper access control flaw in the @payloadcms/storage-vercel-blob storage adapter for Payload. It allows authenticated users to bypass collection-level permissions by directly accessing the client-upload route. Attackers can upload files without the required permissions, bypassing intended access controls.

Detection Guidance

To detect this vulnerability, check Payload CMS logs for unauthorized access attempts to the client-upload route. Look for POST requests to /client-upload with file uploads from users without proper collection permissions. Monitor for unexpected file uploads in storage buckets linked to Payload CMS.

Impact Analysis

An attacker could upload unauthorized files to your Payload system, potentially leading to data leaks, unauthorized content, or further exploitation. This could compromise data integrity and confidentiality if sensitive files are uploaded without proper permissions.

Compliance Impact

This vulnerability could lead to unauthorized data access or uploads, violating compliance requirements for GDPR (data protection) and HIPAA (health data privacy). It may result in unauthorized data exposure, non-compliance with access control policies, and potential legal penalties.

Mitigation Strategies

Immediately update the @payloadcms/storage-vercel-blob package to the latest patched version. Review and restrict access to the client-upload endpoint via firewall rules or server configuration. Audit recent file uploads for unauthorized activity and revoke access for suspicious users.

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