Bug 2481506 (CVE-2026-48683)

Summary: CVE-2026-48683 fastnetmon: FastNetMon: Information disclosure or Denial of Service via out-of-bounds read in NetFlow v9 processing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in FastNetMon Community Edition. This out-of-bounds read vulnerability in the NetFlow v9 data flowset processor allows a remote attacker to send specially crafted templates over unauthenticated UDP. This can lead to the disclosure of sensitive memory contents or cause a denial of service (DoS) by crashing the application.
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Bug Depends On: 2482671, 2482672    
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Description OSIDB Bzimport 2026-05-26 16:02:15 UTC 
FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read vulnerability in the NetFlow v9 data flowset processor. In src/netflow_plugin/netflow_v9_collector.cpp, the Data template branch (lines 1695-1702) iterates over flow records without performing a per-iteration bounds check against the packet end pointer. In contrast, the Options template branch (lines 1709-1719) correctly checks 'if (pkt + offset + field_template->total_length > packet_end)' before each iteration. The Data branch omits this check entirely. Since template definitions are sent by the network peer (and are unauthenticated UDP), an attacker can craft templates that cause the parser to read arbitrary memory past the packet buffer. This can leak sensitive memory contents or cause a crash.