CVE-2026-61684: FastGPT: Unauthenticated cross-tenant data access via forgeable plugin-invoke JWT (default INVOKE_TOKEN_SECRET='token')
FastGPT is a knowledge-based AI application platform. In 4.15.0-beta4, FastGPT plugin invoke reverse-call endpoints under /api/invoke/ authenticate only by verifying a JWT signed with INVOKETOKENSECRET, which defaults to the constant string token and was not set in official deployment templates. An unauthenticated attacker can self-sign an HS256 JWT and reach /api/invoke/userInfo to disclose cross-tenant user PII by attacker-supplied tmbId values, or /api/invoke/fileUpload to write attacker-controlled content into chat files. This issue is fixed in version 4.15.0-beta5.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
FastGPTto a version that resolves this vulnerability.Fixed in 4.15.0-beta5 - Configuration
In your official deployment configuration, set FastGPT's INVOKE_TOKEN_SECRET to a strong, unique value rather than leaving the default constant string "token", so that /api/invoke/* endpoints cannot be accessed using forgeable plugin-invoke JWTs.
FastGPT plugin invoke token configuration INVOKE_TOKEN_SECRET = (set to a non-default secret; do not use the constant string "token")
Event History
Frequently Asked Questions
What is the severity of CVE-2026-61684?
CVE-2026-61684 has a high severity rating of 8.8.
What does CVE-2026-61684 exploit?
CVE-2026-61684 exploits unauthenticated cross-tenant data access via a forgeable plugin-invoke JWT.
How do I fix CVE-2026-61684?
To fix CVE-2026-61684, ensure that the INVOKE_TOKEN_SECRET is set to a secure, unique value instead of the default 'token'.
Which version of FastGPT is affected by CVE-2026-61684?
CVE-2026-61684 affects FastGPT version 4.15.0-beta4.
What are the implications of CVE-2026-61684?
The implications of CVE-2026-61684 include potential unauthorized access to sensitive data across different tenants.