CVE-2026-42345 PUBLISHED

FastGPT: Cloud metadata endpoint SSRF protection bypass via port specification, IPv6 mapping, hex/decimal IP encoding, and trailing dot

Assigner: GitHub_M
Reserved: 26.04.2026 Published: 08.05.2026 Updated: 08.05.2026

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 blocks cloud metadata endpoints using a fullUrl.startsWith() check against a hardcoded list. This check can be bypassed using at least 7 different URL encoding techniques, all of which resolve to the same cloud metadata service but do not match the blocklist patterns. Additionally, the broader private IP check (isInternalIPv4/isInternalIPv6) is disabled by default because CHECK_INTERNAL_IP defaults to false (not 'true'), so these bypasses reach the metadata endpoint without any further validation. At time of publication, there are no publicly available patches.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
CVSS Score: 7.7

Product Status

Vendor labring
Product FastGPT
Versions
  • Version <= 4.14.11 is affected

References

Problem Types

  • CWE-918: Server-Side Request Forgery (SSRF) CWE