---
id: "CVE-2026-92693"
page: "https://infrastack.ai/live/CVE-2026-92693"
kind: "vulnerability"
aliases: ["CVE-2026-92693"]
title: "FastNetMon: crafted sFlow packet triggers out-of-bounds read remotely"
severity: "high"
cvss: 8.2
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "fastnetmon", "fixed": [], "affected": "<= 1.2.9", "ecosystem": "github"}]
ecosystems: []
tags: ["ddos-detection", "fastnetmon", "network-monitoring", "package", "sflow"]
not_affected_if: ["isolated-management-network", "sflow-disabled"]
published_at: "2026-11-05T23:17:01+00:00"
first_seen_at: "2026-11-05T23:48:40+00:00"
updated_at: "2026-11-05T23:51:33+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-92693", "first_seen_at": "2026-11-05T23:48:40+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-11-05T23:51:33+00:00"}]
exploit_sources: []
---

# FastNetMon: crafted sFlow packet triggers out-of-bounds read remotely

Link for people: https://infrastack.ai/live/CVE-2026-92693 (this .md is for agents)

FastNetMon, a DDoS detector, reads past the end of a packet buffer when parsing a crafted IPv6 fragment header inside sFlow v5 data. An unauthenticated remote sender can make the detector read memory it should not, which may leak or disrupt data.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- github:fastnetmon affected <= 1.2.9 fixed no fixed version listed

## How to check

- Run fastnetmon --version; 1.2.9 and earlier are affected, and no release is patched yet.
- Check whether the sFlow collector is enabled in fastnetmon.conf and whether its UDP port is reachable from untrusted networks (firewall or ACL it to your routers only).
- If you build from source, check that your tree includes commit 1da80df73620c6d0aa4462e9611e65047529b12a.
- The advisory does not say whether the sFlow listener is on by default; check your config.

## Fix

No patched release: the advisory lists patched versions as None (affected <= 1.2.9). The upstream commit 1da80df (2026-07-20) adds the missing bounds check; until a release ships, build from master at or after that commit, or keep the sFlow listener off untrusted networks.

## Timeline

- 2026-11-05T23:48:40+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-92693
- 2026-11-05T23:51:33+00:00 analyst — Read GHSA-jmjw-392h-4g93 and the fix commit. Patched versions None; fix on master only. Advisory shows ASan out-of-bounds read of 2 bytes in a harness, not a production crash; no exploitation reported. Default sFlow state not stated. X skipped (no search done).

## Documents

- [advisory] Vendor advisory: github.com https://github.com/pavel-odintsov/fastnetmon/security/advisories/GHSA-jmjw-392h-4g93
- [fix] Patch: github.com https://github.com/pavel-odintsov/fastnetmon/commit/1da80df73620c6d0aa4462e9611e65047529b12a

## From the sources

FastNetMon is a high-performance DDoS detector and sensor. In version 1.2.9 and earlier, parse_raw_packet_to_simple_packet_full() in src/simple_packet_parser_ng.cpp dereferences ipv6_extension_header_fragment_t when IpProtocolNumberIPV6_FRAG is present without first verifying that the eight-byte Fragment header remains. A crafted sFlow v5 RAW_PACKET_HEADER record can remotely reach this shared parser with the Fragment bytes omitted, causing an unauthenticated remote out-of-bounds read. The supplied harness detects the read under AddressSanitizer, but the advisory does not establish a production process crash. No fixed release is available as of this review.

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