CVE-2026-42344
FastGPT: DNS rebinding TOCTOU bypass in isInternalAddress allows SSRF on all protected endpoints
Description
FastGPT is an AI Agent building platform. In versions 4.14.11 and prior, FastGPT's isInternalAddress() function in packages/service/common/system/utils.ts is vulnerable to DNS rebinding (TOCTOU — Time-of-Check to Time-of-Use). The function resolves the hostname via dns.resolve4()/dns.resolve6() and checks resolved IPs against private ranges, but the actual HTTP request happens in a separate call with a new DNS resolution, allowing the DNS record to change between validation and fetch. At time of publication, there are no publicly available patches.
INFO
Published Date :
May 8, 2026, 11:16 p.m.
Last Modified :
July 24, 2026, 9:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update FastGPT to a version with DNS rebinding protection.
- Implement strict DNS resolution validation.
- Validate target IP addresses before requests.
- Monitor network traffic for suspicious activity.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-42344.
| URL | Resource |
|---|---|
| https://github.com/labring/FastGPT/security/advisories/GHSA-cc8x-jrqv-hmwh | |
| https://github.com/labring/FastGPT/security/advisories/GHSA-cc8x-jrqv-hmwh |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-42344 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-42344
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-42344 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-42344 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Translated by [email protected]
Jul. 24, 2026
Action Type Old Value New Value Added Translation Title: FastGPT de labring, Description: FastGPT es una plataforma de creación de agentes de IA. En las versiones 4.14.11 y anteriores, la función isInternalAddress() de FastGPT en packages/service/common/system/utils.ts es vulnerable a la reencuadernación de DNS (TOCTOU - Tiempo de verificación a tiempo de uso). La función resuelve el nombre de host a través de dns.resolve4()/dns.resolve6() y verifica las IP resueltas contra rangos privados, pero la solicitud HTTP real ocurre en una llamada separada con una nueva resolución de DNS, lo que permite que el registro DNS cambie entre la validación y la recuperación. En el momento de la publicación, no hay parches disponibles públicamente. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'labring', 'product': 'FastGPT', 'versions': [{'status': 'affected', 'version': '<= 4.14.11'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-42344', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-05-11T18:03:09.390132Z'} -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 11, 2026
Action Type Old Value New Value Added Reference https://github.com/labring/FastGPT/security/advisories/GHSA-cc8x-jrqv-hmwh -
New CVE Received by [email protected]
May. 08, 2026
Action Type Old Value New Value Added Description FastGPT is an AI Agent building platform. In versions 4.14.11 and prior, FastGPT's isInternalAddress() function in packages/service/common/system/utils.ts is vulnerable to DNS rebinding (TOCTOU — Time-of-Check to Time-of-Use). The function resolves the hostname via dns.resolve4()/dns.resolve6() and checks resolved IPs against private ranges, but the actual HTTP request happens in a separate call with a new DNS resolution, allowing the DNS record to change between validation and fetch. At time of publication, there are no publicly available patches. Added CVSS V3.1 AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N Added CWE CWE-367 Added Reference https://github.com/labring/FastGPT/security/advisories/GHSA-cc8x-jrqv-hmwh