PT-2026-43377 · Unknown · Fastnetmon Community Edition

Published

2026-05-26

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Updated

2026-05-27

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CVE-2026-48689

CVSS v3.1

9.8

Critical

VectorAV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Name of the Vulnerable Software and Affected Versions FastNetMon Community Edition versions prior to 1.2.10
Description An off-by-one heap-based buffer overflow exists in the dynamic binary buffer t class within the src/dynamic binary buffer.hpp file. The issue stems from an incorrect bounds check in five methods: append dynamic buffer(), append data as pointer(), append data as object ptr(), memcpy from ptr(), and memcpy from object ptr(). These methods use the check if (offset + length > maximum internal storage size + 1) instead of if (offset + length > maximum internal storage size), allowing one byte to be written past the end of the heap-allocated buffer. This class is used for BGP message encoding/decoding, NetFlow template processing, and Flow Spec NLRI construction. An attacker sending network traffic such as NetFlow, sFlow, IPFIX, or BGP can trigger this overflow, which may lead to arbitrary code execution by corrupting heap metadata.
Recommendations Update FastNetMon Community Edition to version 1.2.10 or later.

Exploit

Fix

Heap Based Buffer Overflow

Memory Corruption

Weakness Enumeration

Related Identifiers

CVE-2026-48689

Affected Products

Fastnetmon Community Edition