---
id: CVE-2026-92698
title: >-
  FastNetMon: sFlow header_size field trusted as parser capture length causes
  remote out-of-bounds read
summary: >-
  FastNetMon is a high-performance DDoS detector and sensor. In version 1.2.9
  and earlier, process_sflow_flow_sample() in
  src/sflow_plugin/sflow_collector.cpp passes the attacker-controlled
  sflow_raw_protocol_header_t.header_size to parse_…
severity: high
cvss: 8.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-125
vendor: pavel-odintsov
product: fastnetmon
affected:
  - fastnetmon <= 1.2.9
published: '2026-11-05'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T22:35:58.969Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-92698'
references:
  - url: >-
      https://github.com/pavel-odintsov/fastnetmon/security/advisories/GHSA-852r-3wcv-pjx2
    label: >-
      https://github.com/pavel-odintsov/fastnetmon/security/advisories/GHSA-852r-3wcv-pjx2
  - url: 'https://github.com/pavel-odintsov/fastnetmon/pull/1089'
    label: 'https://github.com/pavel-odintsov/fastnetmon/pull/1089'
  - url: 'https://github.com/pavel-odintsov/fastnetmon/pull/1093'
    label: 'https://github.com/pavel-odintsov/fastnetmon/pull/1093'
  - url: >-
      https://github.com/pavel-odintsov/fastnetmon/commit/6871b7383322db14405a8de1399a83da15ef3533
    label: >-
      https://github.com/pavel-odintsov/fastnetmon/commit/6871b7383322db14405a8de1399a83da15ef3533
  - url: >-
      https://github.com/pavel-odintsov/fastnetmon/commit/be81c403b9aa891f8444a6379cd4a4fbbc324a83
    label: >-
      https://github.com/pavel-odintsov/fastnetmon/commit/be81c403b9aa891f8444a6379cd4a4fbbc324a83
tags:
  - cve.org
ingestedAt: '2026-11-05T23:41:31.942Z'
epss: 0.00323
epssPercentile: 0.25539
---

## Overview

FastNetMon is a high-performance DDoS detector and sensor. In version 1.2.9 and earlier, process_sflow_flow_sample() in src/sflow_plugin/sflow_collector.cpp passes the attacker-controlled sflow_raw_protocol_header_t.header_size to parse_raw_packet_to_simple_packet_full() as its trusted captured length without comparing it with the bytes remaining in the record. An inflated header_size creates a false end pointer beyond the received sFlow v5 UDP buffer, defeating the nested parser's bounds checks and causing an unauthenticated remote out-of-bounds read and process crash, with possible limited exposure of adjacent bytes through parsed flow fields. No fixed release is available as of this review.

## Affected

- `fastnetmon <= 1.2.9`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.