FastGPT — Vulnerability (CVE-2026-42344)
Date: 2026-05
Attack vector: other
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2026-42344
CWE: CWE-367
CVSS: 6.3 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N)

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.


Mitigations:

Architectural layers (MAESTRO):