CVE-2026-30231 in Flare
Summary
by MITRE • 03/06/2026
Flare is a Next.js-based, self-hostable file sharing platform that integrates with screenshot tools. Prior to version 1.7.2, the raw and direct file routes only block unauthenticated users from accessing private files. Any authenticated, non‑owner user who knows the file URL can retrieve the content, which is inconsistent with stricter checks used by other endpoints. This issue has been patched in version 1.7.2.
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Analysis
by VulDB Data Team • 03/06/2026
The vulnerability identified as CVE-2026-30231 affects Flare, a Next.js-based file sharing platform that integrates with screenshot tools. This security flaw represents a significant authorization bypass issue that undermines the platform's access control mechanisms. The vulnerability specifically impacts how the application handles file access permissions for authenticated users who are not the original file owners. Prior to version 1.7.2, the platform implemented a flawed access control model that fails to properly validate user permissions when accessing files through direct routes. The system correctly blocks unauthenticated users from accessing private files, but it inadequately protects against authenticated users who possess knowledge of specific file URLs. This creates a scenario where any authenticated user can retrieve content they should not have access to, simply by knowing the direct file URL. The inconsistency in access control validation between different endpoints within the same application demonstrates a fundamental flaw in the platform's security architecture.
The technical implementation of this vulnerability stems from improper authorization checks in the raw and direct file routes. These routes implement a weak access control mechanism that only verifies authentication status but fails to validate whether the authenticated user has proper authorization to access the specific file resource. This flaw allows for privilege escalation through information disclosure, as any authenticated user can exploit their knowledge of file URLs to access private content belonging to other users. The vulnerability directly relates to CWE-285, which addresses improper authorization in software systems, and more specifically aligns with CWE-284, which covers improper access control. The issue demonstrates a classic case of insufficient authorization checks where the system assumes that authentication is sufficient for access control rather than implementing proper role-based or ownership-based access validation.
The operational impact of this vulnerability is substantial for organizations using Flare as their file sharing platform. Attackers who gain access to the platform through legitimate authentication methods can exploit this flaw to access private files belonging to other users, potentially leading to data breaches, privacy violations, and unauthorized information disclosure. The vulnerability affects the confidentiality and integrity of user data, as it allows unauthorized access to private content that should only be accessible to file owners or authorized individuals. This issue particularly impacts organizations that rely on Flare for sharing sensitive documents, proprietary information, or personal data, as the vulnerability could result in significant data exposure. The impact is amplified because the vulnerability requires minimal technical expertise to exploit, as it only requires knowledge of the target file URL and authentication to the platform.
The remediation for this vulnerability involves implementing proper authorization checks in the raw and direct file routes. Version 1.7.2 of Flare addresses this issue by ensuring that all file access requests undergo proper validation of user permissions against the file ownership or access rights. The fix should implement a consistent authorization model across all endpoints, ensuring that authenticated users must prove their authorization to access specific files regardless of whether they are the original owners. Security measures should include validating the relationship between the authenticated user and the target file, implementing proper access control lists, and ensuring that file access permissions are consistently enforced across all application routes. Organizations should also consider implementing additional monitoring for unauthorized file access attempts and establishing proper audit trails to detect potential exploitation of this vulnerability. The solution aligns with ATT&CK technique T1078 which covers valid accounts and T1566 which addresses credential access through social engineering, as this vulnerability allows unauthorized access through legitimate authentication mechanisms.