Bug 2481503 (CVE-2026-48692)

Summary: CVE-2026-48692 fastnetmon: FastNetMon Community Edition: Denial of Service and arbitrary script execution via unauthenticated gRPC API
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in FastNetMon Community Edition. The gRPC API server, exposed on port 50052, operates without any authentication mechanism. A remote attacker with local network access can exploit this vulnerability to ban arbitrary IP addresses, resulting in a denial of service for legitimate network traffic. Additionally, an attacker can unban active attacks, disabling DDoS mitigation, and trigger the execution of arbitrary scripts.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2482675, 2482676    
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Description OSIDB Bzimport 2026-05-26 16:02:04 UTC 
FastNetMon Community Edition through 1.2.9 exposes a gRPC API server on port 50052 with no authentication mechanism. The server is initialized with grpc::InsecureServerCredentials() (src/fastnetmon.cpp line 477) and a source code comment explicitly acknowledges 'Listen on the given address without any authentication mechanism.' None of the RPC methods in src/api.cpp (ExecuteBan, ExecuteUnBan, GetBanlist, GetTotalTrafficCounters, etc.) perform any credential verification. The ExecuteBan and ExecuteUnBan methods trigger security-critical actions: BGP route announcements that can blackhole network traffic, and execution of external notification scripts via popen(). An attacker with local network access can ban arbitrary IP addresses (causing denial of service to legitimate traffic), unban active attacks (disabling DDoS mitigation), and trigger script execution. There is also no role-based access control separating read-only monitoring from destructive administrative operations.