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Vulnerability · Published Nov 5, 2026 · Assigned by GitHub_M

CVE-2026-93424FastNetMon: NetFlow/IPFIX template cache returns unlocked pointers, causing heap-use-after-free on multi-port deployments

High 7.5

In plain English

A high-severity use-after-free 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 20% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.3%top 79.6% 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, peer_find_template() in src/netflow_plugin/netflow_collector.cpp and src/netflow_plugin/netflow_v9_collector.cpp returns a pointer into global_netflow9_templates after releasing the cache mutex. On deployments with at least two entries in netflow_ports, concurrent template redefinition and data-flowset processing can let add_update_peer_template() reassign the template and free its records vector while another listener dereferences the escaped pointer. An unauthenticated sender that can reach both NetFlow/IPFIX listener ports can trigger a heap-use-after-free and reliably crash FastNetMon. No fixed release is available as of this review.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12fastnetmonno fix listedDEBIAN-CVE-2026-93424
Debian:13fastnetmonno fix listedDEBIAN-CVE-2026-93424
Debian:14fastnetmonno fix listedDEBIAN-CVE-2026-93424
Ubuntu:26.10fastnetmonno fix listedUBUNTU-CVE-2026-93424

Affected products (as reported)

VendorProductVersions
pavel-odintsov fastnetmon <= 1.2.9

Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References