CVE-2026-42344: medium-severity vulnerability in labring FastGPT
FastGPT: DNS rebinding TOCTOU bypass in isInternalAddress allows SSRF on all protected endpoints
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.3epss 0.1%
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.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N
Affected products
labring · FastGPTRelated CVEs — labring FastGPT
In the same product, most dangerous first.
CVE-2026-42302CRITICALFastGPT: Unauthenticated Remote Code Execution (RCE) via code-server Misconfiguration in agent-sandboxEPSS 0.7%CVE-2026-40351CRITICALFastGPT: NoSQL Injection in loginByPassword leads to Authentication BypassEPSS 0.6%CVE-2025-49131MEDIUMFastGPT Sandbox Vulnerable to Sandbox BypassEPSS 0.5%CVE-2026-55418HIGHFastGPT: S3 presign/read handlers do not bind the object key to the caller's team (cross-team file disclosure)EPSS 0.5%CVE-2026-68929CRITICALFastGPT: Unauthenticated WeChat channel hijack and denial of service via shareId-only authorizationEPSS 0.4%CVE-2026-34162CRITICALFastGPT: Unauthenticated SSRF via httpTools Endpoint Leads to Internal API Key TheftEPSS 0.4%