CVE-2026-40351: fastgpt — Exploit & Fix

Description

FastGPT is an AI Agent building platform. In versions prior to 4.14.9.5, the password-based login endpoint uses TypeScript type assertion without runtime validation, allowing an unauthenticated attacker to pass a MongoDB query operator object (e.g., {"$ne": ""}) as the password field. This NoSQL injection bypasses the password check, enabling login as any user including the root administrator. This issue has been fixed in version 4.14.9.5.

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CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0007

Probability of exploitation

0.21%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-943 CWE-943

Affected Products

Vendor	Product	Versions
fastgpt	fastgpt	< 4.14.9.5

References

Advisories & Patches

https://github.com/labring/FastGPT/commit/bd966d479fbe414d02679cf79f9eaaab3d100a2d https://github.com/labring/FastGPT/security/advisories/GHSA-x8mx-2mr7-h9xg

Exploits

https://github.com/labring/FastGPT/security/advisories/GHSA-x8mx-2mr7-h9xg

Other References

https://github.com/labring/FastGPT/releases/tag/v4.14.9.5

Frequently Asked Questions

What is CVE-2026-40351? +

FastGPT is an AI Agent building platform. In versions prior to 4.14.9.5, the password-based login endpoint uses TypeScript type assertion without runtime validation, allowing an unauthenticated attacker to pass a MongoDB query operator object (e.g., {"$ne": ""}) as the password field. This NoSQL injection bypasses the password check, enabling login as any user including the root administrator. This issue has been fixed in version 4.14.9.5. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-40351? +

CVE-2026-40351 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0007, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-40351? +

CVE-2026-40351 affects products from fastgpt, specifically: fastgpt. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-40351? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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