CVE-2026-18424
Concrete CMS 9.0.0 to 9.5.2 is vulnerable to SSRF protection bypass in remote file import when multiple URLs share a host but use different ports
Description
Concrete CMS 9.0.0 to 9.5.2 is vulnerable to Server-Side Request Forgery iremote file import via cross-port reuse of a host's validated DNS pin. When multiple remote URLs share the same host, only the first `ValidatedRemoteUrl` is retained and reused for every later URL with that host. A low-privileged authenticated user permitted to import files could therefore supply a DNS-rebinding host that resolved to a public address during validation and to a private or loopback address during the unpinned download, causing the server to fetch internal-only resources such as loopback services, internal admin panels, or cloud metadata endpoints and to save the responses into the file manager. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N. Thanks Ahmad Wicaksono (sonix03) for reporting.
CVSS Vector Breakdown
AV:NAttack VectorAC:HAttack ComplexityPR:LPrivileges RequiredUI:NUser InteractionS:CScopeC:HConfidentialityI:LIntegrityA:NAvailabilityWeaknesses
Affected Products
Exploitability
Attack Graph
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MITRE ATT&CK
2 techniquesReferences
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