CVE-2026-84301
Deferred Deferred - Pending Action

FastGPT DNS Rebinding via Axios Interceptor Before 4.15.2

Publication date: 2026-09-22

Last updated on: 2026-09-22

Assigner: GitHub, Inc.

Description
FastGPT is an open-source LLM platform for building AI applications on a knowledge base. Prior to 4.15.2, the safe Axios request interceptor in packages/service/common/api/axios.ts validates a hostname with isInternalAddress() before a later HTTP connection performs an independent DNS lookup, creating a DNS rebinding window, allowing an attacker-controlled hostname to resolve publicly during the check and to a loopback, private, link-local, or metadata address during connection. An authenticated attacker who can supply a URL to a safe-Axios-backed HTTP tool, workflow HTTP node, external file fetch, or other server-side integration can use this time-of-check/time-of-use gap to reach services that direct private-address inputs would block. The same independent re-resolution occurs after manual redirect hops because each redirect target is checked before a separate connection lookup. This issue is fixed in version 4.15.2.

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Meta Information

Published
2026-09-22
Last Modified
2026-09-22
Generated
2026-09-22
AI Q&A
2026-09-22
EPSS Evaluated
N/A
NVD
CVE-2026-84301
EUVD
EUVD-2026-84559

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
labring fastgpt 4.15.2
labring fastgpt to 4.15.2 (exc)
fastgpt fastgpt 4.15.2

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Attack-Flow Graph

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Executive Summary

This vulnerability is a DNS rebinding and Time-of-Check/Time-of-Use (TOCTOU) issue in FastGPT versions before 4.15.2. The safe Axios interceptor checks a hostname's address before making an HTTP connection but does not reuse the resolved IP for the actual connection. This allows an attacker to supply a URL that resolves publicly during the check but to a private or internal address during the connection, bypassing SSRF protections.

Detection Guidance

To detect this vulnerability, monitor DNS resolution patterns for FastGPT services. Check if FastGPT versions prior to 4.15.2 are running. Inspect network logs for unexpected outbound connections to loopback, private, or metadata addresses from FastGPT processes. Use tools like tcpdump or Wireshark to capture DNS queries and HTTP requests originating from FastGPT.

Impact Analysis

An authenticated attacker could exploit this to access internal network services, loopback addresses, or metadata endpoints on the server side by supplying a malicious URL. This could lead to unauthorized data access, service disruption, or further network compromise depending on the exposed services.

Compliance Impact

This vulnerability could violate compliance requirements like GDPR or HIPAA by allowing unauthorized access to internal systems or sensitive data. Exposure of internal services may lead to data breaches, unauthorized processing, or failure to maintain data confidentiality and integrity.

Mitigation Strategies

Upgrade FastGPT to version 4.15.2 or later immediately. Disable or restrict access to HTTP tools, workflow HTTP nodes, and external file fetches that use the vulnerable safe-axios interceptor until patched. Review and update network policies to block outbound connections to internal addresses from FastGPT servers.

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