CVE-2026-48688 Affecting fastnetmon package, versions <1.2.9-0+deb13u1


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.28% (21st percentile)

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  • Snyk IDSNYK-DEBIAN13-FASTNETMON-17089109
  • published29 May 2026
  • disclosed26 May 2026

Introduced: 26 May 2026

CVE-2026-48688  (opens in a new tab)

How to fix?

Upgrade Debian:13 fastnetmon to version 1.2.9-0+deb13u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream fastnetmon package and not the fastnetmon package as distributed by Debian. See How to fix? for Debian:13 relevant fixed versions and status.

FastNetMon Community Edition through 1.2.9 contains multiple out-of-bounds reads in the BGP MP_REACH_NLRI IPv6 attribute decoder. The function decode_mp_reach_ipv6() in src/bgp_protocol.cpp contains a TODO comment at line 156 explicitly acknowledging 'we should add sanity checks to avoid reads after attribute memory block.' The function casts raw pointers to structure types without verifying sufficient data exists (line 158), uses the attacker-controlled length_of_next_hop field to determine memcpy size (line 181), and computes prefix_length by dereferencing a pointer calculated from multiple attacker-controlled offsets without bounds validation (line 189). The prefix_length is then used to calculate number_of_bytes_required_for_prefix which becomes a memcpy length (line 202) with no check against remaining buffer size.

CVSS Base Scores

version 3.1