EUVD-2026-42427
GHSA-hf3x-9vx4-94qv
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Unauthenticated low-complexity network SSRF (PR:N/AC:L) with a scope change (S:C) as it reads other internal systems; confidentiality impact only (C:H), no integrity or availability effect.
Primary rating from Vendor (vulncheck).
CVSS VectorVendor: vulncheck
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
2DescriptionCVE.org
Monsta FTP before 2.14.5 contains a server-side request forgery vulnerability in the fetchRemoteFile action caused by an incomplete IP blocklist check in the isBlockedIP() function, which fails to detect embedded IPv4 addresses within IPv4-mapped IPv6 addresses. An unauthenticated attacker can obtain a CSRF token from the public getSystemVars endpoint and submit a fetchRemoteFile request with a source URL resolving to an IPv4-mapped address, causing the server to issue HTTP requests to internal services and write responses to an attacker-controlled FTP destination, enabling retrieval of cloud instance metadata credentials.
AnalysisAI
Server-side request forgery in Monsta FTP before 2.14.5 lets an unauthenticated remote attacker coerce the server into making HTTP requests to internal-only services and exfiltrate the responses. The flaw lives in the fetchRemoteFile action, where the isBlockedIP() SSRF filter fails to recognize IPv4-mapped IPv6 addresses, so blocklisted internal ranges can be reached anyway; a CSRF token is trivially obtainable from the public getSystemVars endpoint. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the target to run Monsta FTP before 2.14.5 with the network-reachable fetchRemoteFile action and the public getSystemVars endpoint available (both present by default), and the attacker must supply a source URL that resolves to an IPv4-mapped IPv6 address so it bypasses isBlockedIP(). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The published CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N, base 7.7) models this as network-reachable, low-complexity, unauthenticated exploitation whose impact falls entirely on subsequent systems (SC:H) rather than the Monsta FTP host itself (VC:N/VI:N/VA:N) - an accurate reflection of SSRF that reads OTHER internal services. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker locates an internet-exposed Monsta FTP instance, requests a CSRF token from the public getSystemVars endpoint, then submits a fetchRemoteFile request with a source URL pointing at an IPv4-mapped IPv6 address (e.g. resolving to ::ffff:169.254.169.254) that the isBlockedIP() filter fails to block. … |
| Remediation | Vendor-released patch: 2.14.5 - upgrade Monsta FTP to 2.14.5 or later, which corrects the isBlockedIP() logic to detect IPv4-mapped IPv6 addresses; see the release notes at https://www.monstaftp.com/notes/ and the advisory at https://www.vulncheck.com/advisories/monsta-ftp-ssrf-via-ipv4-mapped-ipv6-address-bypass. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
24 hours: Inventory all Monsta FTP deployments, document versions, and immediately restrict network access from untrusted sources via firewall rules. …
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Same weakness CWE-918 – Server-Side Request Forgery (SSRF)
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External POC / Exploit Code
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