# CVE-2026-40100: labring FastGPT SSRF in mcpTools runTool endpoint

Source: https://junglewise.ai/threats/cve-2026-40100-labring-fastgpt-ssrf-in-mcptools-runtool-endpoint  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-10. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2026-40100 · Severity: medium · CVSS 5.3 · Published 2026-04-10

FastGPT, an AI agent building platform, contains a security flaw that allows unauthorized individuals to probe internal network resources. By sending specially crafted requests to a specific tool-running component, an attacker can bypass security checks and access private internal services that are not intended to be public. This could lead to the exposure of sensitive internal data or information about the organization's private infrastructure.

Technologies: [Fastgpt](https://junglewise.ai/threats/technologies/fastgpt). Vendors: [Fastgpt](https://junglewise.ai/threats/vendors/fastgpt).

## Quick answers

**Is CVE-2026-40100 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40100 being exploited in the wild.

**How severe is CVE-2026-40100?** Medium severity, with a CVSS score of 5.3, published 10 April 2026.

**Which products and versions are affected?** labring FastGPT < 4.14.10.3.

**Is there a fix for CVE-2026-40100?** A patch was published on 2026-04-10. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-40100 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-40100?** Check whether you run Fastgpt. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A Server-Side Request Forgery (SSRF) vulnerability exists in FastGPT's /api/core/app/mcpTools/runTool endpoint. The root cause is twofold: the endpoint lacks authentication middleware, and the internal IP validation function (isInternalAddress) is disabled by default, only blocking private IPs if the CHECK_INTERNAL_IP environment variable is explicitly set to 'true'. An unauthenticated remote attacker can provide an arbitrary URL in the 'url' parameter, causing the server to make requests to internal network resources. This can be used to scan internal ports or access internal services. The vulnerability is addressed in version 4.14.10.3.

## Affected products

- labring FastGPT < 4.14.10.3

## Timeline

- 2026-04-10: disclosed
- 2026-04-10: advisory
- 2026-04-10: patched

## References

- [https://github.com/labring/FastGPT/security/advisories/GHSA-jrhc-f3j7-f8g4](https://github.com/labring/FastGPT/security/advisories/GHSA-jrhc-f3j7-f8g4)

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