labring FastGPT 4.15.0-beta4 Plugin Invoke /api/invoke authenticate tmbId information disclosure

Summaryinfo

A vulnerability marked as problematic has been reported in labring FastGPT 4.15.0-beta4. Impacted is the function Authenticate of the file /api/invoke of the component Plugin Invoke. This manipulation of the argument tmbId causes information disclosure. This vulnerability is registered as CVE-2026-61684. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in labring FastGPT 4.15.0-beta4. It has been declared as problematic. Affected by this vulnerability is the function authenticate of the file /api/invoke of the component Plugin Invoke. The manipulation of the argument tmbId with an unknown input leads to a information disclosure vulnerability. The CWE definition for the vulnerability is CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. As an impact it is known to affect confidentiality. The summary by CVE is:

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 INVOKE_TOKEN_SECRET, 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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-61684 since 07/10/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1592 for this issue.

Upgrading to version 4.15.0-beta5 eliminates this vulnerability.

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Productinfo

Vendor

• labring

Name

• FastGPT

Version

• 4.15.0-beta4

Website

• Product: https://github.com/labring/FastGPT/

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