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

Summary

CVECVE-2026-42345
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-08 23:16:37 UTC
Updated2026-05-08 23:16:37 UTC
DescriptionFastGPT 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.

Risk And Classification

Primary CVSS: v3.1 7.7 HIGH from [email protected]

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

Problem Types: CWE-918 | CWE-918 CWE-918: Server-Side Request Forgery (SSRF)


VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.7HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
3.1CNADECLARED7.7HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Labring FastGPT affected <= 4.14.11 Not specified

References

ReferenceSourceLinkTags
github.com/labring/FastGPT/security/advisories/GHSA-jhqw-944x-xh94 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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