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CVE-2026-48692 Pavel Odintsov CVE debrief

FastNetMon Community Edition through 1.2.9 exposes an unauthenticated gRPC API on TCP port 50052. The server uses grpc::InsecureServerCredentials() and implements no credential verification across RPC methods including ExecuteBan, ExecuteUnBan, GetBanlist, and GetTotalTrafficCounters. ExecuteBan and ExecuteUnBan trigger BGP route announcements and external script execution via popen(). An attacker with local network access can induce denial of service by banning arbitrary addresses, disable DDoS mitigation by unbanning active threats, and trigger script execution. No role-based access control separates read operations from destructive administrative functions.

Vendor
Pavel Odintsov
Product
Fastnetmon
CVSS
HIGH 8.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-26
Original CVE updated
2026-05-27
Advisory published
2026-05-26
Advisory updated
2026-05-27

Who should care

Network security engineers operating FastNetMon Community Edition for DDoS detection and mitigation; infrastructure teams managing BGP-connected DDoS scrubbing centers; security operations centers monitoring for unauthorized configuration changes; compliance auditors evaluating access controls for critical network infrastructure.

Technical summary

The vulnerability exists in FastNetMon Community Edition's gRPC server implementation. The server binds to 0.0.0.0:50052 using grpc::InsecureServerCredentials(), explicitly disabling all authentication. The api.cpp RPC service implementation performs no credential validation before executing security-sensitive operations. ExecuteBan triggers BGP route announcements to upstream routers (typically blackholing /32 or /128 prefixes) and executes notification scripts via popen(). ExecuteUnBan reverses these actions. The absence of authentication, authorization, and transport security enables any adjacent network actor to manipulate DDoS mitigation state and potentially execute arbitrary commands through script injection if notification scripts process unsanitized input.

Defensive priority

HIGH

Recommended defensive actions

  • Block TCP port 50052 at host firewall and network perimeter unless explicitly required for operational purposes
  • Implement network segmentation to restrict gRPC API access to authorized administrative hosts only
  • Upgrade to FastNetmon Community Edition version 1.2.10 or later when available, or apply vendor-provided authentication patches
  • Monitor for unauthorized connections to port 50052 and anomalous BGP route announcements from FastNetMon instances
  • Review and audit ExecuteBan/ExecuteUnBan RPC invocations in environment logs for unauthorized activity
  • Consider deploying TLS mutual authentication or API key validation if modifying source code locally
  • Evaluate migration to FastNetMon Advanced or Enterprise editions which may provide authentication mechanisms

Evidence notes

CVE description cites specific source file locations: src/fastnetmon.cpp line 477 for InsecureServerCredentials initialization, and src/api.cpp for RPC method implementations. CVSS 3.1 vector AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N reflects adjacent network attack vector with high confidentiality and integrity impact. CWE-306 (Missing Authentication for Critical Function) identified.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-48692 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-48692

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-48692 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-48692

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.