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Vulnerability · Published Nov 5, 2026 · Assigned by GitHub_M

CVE-2026-92698FastNetMon: sFlow header_size field trusted as parser capture length causes remote out-of-bounds read

High 8.2

In plain English

A high-severity out-of-bounds read in fastnetmon from pavel-odintsov. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities).

Severity (CVSS 3.1)8.2High
Exploit odds (30 days)0.3%top 74.5% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12fastnetmonno fix listedDEBIAN-CVE-2026-92698
Debian:13fastnetmonno fix listedDEBIAN-CVE-2026-92698
Debian:14fastnetmonno fix listedDEBIAN-CVE-2026-92698
Ubuntu:26.10fastnetmonno fix listedUBUNTU-CVE-2026-92698

Affected products (as reported)

VendorProductVersions
pavel-odintsov fastnetmon <= 1.2.9

Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

References