CVE-2026-48684

fastnetmon: FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read in the NetFlow v9 options template parser

CVE-2026-48684 is fixed in fastnetmon on 1 platform, first by DEBIAN-CVE-2026-48684, released June 24, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine
CVSS
6.5
medium
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0026
18th percentile

FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read in the NetFlow v9 options template parser. In process_netflow_v9_options_template() (src/netflow_plugin/netflow_v9_collector.cpp), the scope parsing loop (lines 224-229) iterates until scopes_offset reaches the attacker-controlled option_scope_length value, reading netflow9_template_flowset_record_t structures at each step. No bounds check validates that (zone_address + scopes_offset + sizeof(record)) stays within the flowset. The same issue affects the options field loop (lines 241-257) with option_length. Furthermore, option_scope_length is not validated to be a multiple of sizeof(netflow9_template_flowset_record_t), potentially causing misaligned reads. An attacker can trigger reads past the end of the UDP packet buffer.

Where it's fixed

ProductFixed inFixReleased
Linux
fastnetmon · Debian 13.5 (trixie) 1.2.9-0+deb13u1 DEBIAN-CVE-2026-48684 Jun 24, 2026
fastnetmon · Debian 14 1.2.9-1 DEBIAN-CVE-2026-48684 Jun 24, 2026

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