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CVE-2026-63506: CVE-2026-63506: Broken Access Control in TinaCMS isAuthorized Authentication Handler

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CVE-2026-63506: Broken Access Control in TinaCMS isAuthorized Authentication Handler

Vulnerability ID: CVE-2026-63506
CVSS Score: 8.8
Published: 2026-09-17

CVE-2026-63506 is a critical authorization bypass vulnerability in TinaCMS self-hosted backend authentication packages (@tinacms/auth and next-tinacms-azure). By exploiting a request-controlled clientID parameter, unauthenticated attackers with an active token for any developer-registered TinaCloud application can bypass tenant boundaries and execute unauthorized administrative operations, including full GraphQL database interactions and arbitrary media management.

TL;DR

A broken access control flaw in TinaCMS's authorization handler allows attackers to bypass authentication on self-hosted instances using their own registered TinaCloud application credentials.

⚠️ Exploit Status: POC

Technical Details

  • CWE ID: CWE-639
  • Attack Vector: Network (AV:N)
  • CVSS Base Score: 8.8 (High)
  • Exploit Status: Proof-of-Concept / Conceptual
  • KEV Status: Not Listed
  • Impact: Bypass of administrative authentication leading to database and asset manipulation

Affected Systems

  • @tinacms/auth
  • next-tinacms-azure
  • tinacms
  • @tinacms/auth: < 1.1.4 (Fixed in: 1.1.4)
  • next-tinacms-azure: < 15.0.1 (Fixed in: 15.0.1)

Code Analysis

Commit: 0a927a4

Fix authentication bypass by verifying identity against server-configured NEXT_PUBLIC_TINA_CLIENT_ID instead of request query parameters

Mitigation Strategies

  • Update @tinacms/auth to 1.1.4 or higher
  • Update next-tinacms-azure to 15.0.1 or higher
  • Explicitly pass NEXT_PUBLIC_TINA_CLIENT_ID to the isAuthorized function
  • Configure runtime verification to ensure clientID environment variables are not empty

Remediation Steps:

  1. Analyze package.json dependencies for vulnerable versions of @tinacms/auth (< 1.1.4) or next-tinacms-azure (< 15.0.1)
  2. Execute npm install @tinacms/auth@1.1.4 next-tinacms-azure@15.0.1 to pull secure versions
  3. Locate self-hosted authentication handlers (e.g., api/tina/[...media].ts or api/gql.ts)
  4. Modify authentication calls to bind the configuration parameter explicitly: isAuthorized(req, process.env.NEXT_PUBLIC_TINA_CLIENT_ID)
  5. Redeploy the application and verify that requests passing arbitrary client IDs are rejected with a 401/403 status code

References

Read the full report for CVE-2026-63506 on our website for more details including interactive diagrams and full exploit analysis.

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