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CVE-2026-42344

FastGPT: DNS rebinding TOCTOU bypass in isInternalAddress allows SSRF on all protected endpoints

Published: May 8, 2026Updated: Jul 24, 2026 Sources: CVE List NVDCWE-367
6.3MEDIUM
NVD MITRE
EPSS Score
0.1%
Top 95.5%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available
Self-Check
Not available

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:HPR:LUI:NS:CC:HI:NA:N
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:NIntegrity
None
A:NAvailability
None
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Weaknesses

CWE-367

Affected Products

labring
commercial
FastGPTSaaS
AI / ML / llm-serving-inference

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique
Privilege Escalation
View detailed technique mapping

References

https://github.com/labring/FastGPT/security/advisories/GHSA-cc8x-jrqv-hmwh
github.com

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