CVE-2026-30230
Published: 06 March 2026
Summary
CVE-2026-30230 is a high-severity Authorization Bypass Through User-Controlled Key (CWE-639) vulnerability in Flintsh Flare. Its CVSS base score is 8.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 29.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-30230 is an authorization bypass vulnerability (CWE-639) in Flare, a Next.js-based, self-hostable file sharing platform that integrates with screenshot tools. In versions prior to 1.7.2, the thumbnail endpoint does not validate passwords for password-protected files, despite checking ownership or admin privileges for private files. This flaw allows unauthorized access to thumbnails without the password. The vulnerability carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) and was published on 2026-03-06T21:16:17.077.
Remote attackers require no privileges or user interaction to exploit this issue over the network. By directly accessing the thumbnail endpoint with the identifier of a password-protected file, an unauthenticated adversary can retrieve the thumbnail image, disclosing potentially sensitive visual content that was meant to be restricted by the password mechanism.
The vulnerability has been patched in Flare version 1.7.2. Additional mitigation details are available in the GitHub security advisory at https://github.com/FlintSH/Flare/security/advisories/GHSA-3x7v-x3r6-mjh7.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-10076
Vulnerability details
Flare is a Next.js-based, self-hostable file sharing platform that integrates with screenshot tools. Prior to version 1.7.2, the thumbnail endpoint does not validate the password for password‑protected files. It checks ownership/admin for private files but skips password verification, allowing thumbnail…
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access without the password. This issue has been patched in version 1.7.2.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Authorization bypass on thumbnail endpoint of public-facing Next.js web app directly enables remote unauthenticated exploitation of an Internet-facing application to access restricted file content.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Enforces approved authorizations for access to resources like thumbnails, directly mitigating the bypass of password validation on the endpoint.
Requires timely remediation of flaws such as the authorization bypass in the thumbnail endpoint, preventing exploitation through patching.
Ensures least privilege by restricting endpoint access to only authorized users with proper password verification for protected files.