pavel-odintsov FastNetMon up to 1.2.9 NetFlow Plugin netflow_collector.cpp peer_find_template use after free

Summaryinfo

A vulnerability described as very critical has been identified in pavel-odintsov FastNetMon up to 1.2.9. The impacted element is the function peer_find_template of the file src/netflow_plugin/netflow_collector.cpp of the component NetFlow Plugin. Such manipulation leads to use after free. This vulnerability is uniquely identified as CVE-2026-93424. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability was found in pavel-odintsov FastNetMon up to 1.2.9. It has been rated as very critical. Affected by this issue is the function peer_find_template of the file src/netflow_plugin/netflow_collector.cpp of the component NetFlow Plugin. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-93424 since 09/17/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 11/05/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• pavel-odintsov

Name

• FastNetMon

Version

• 1.2.0
• 1.2.1
• 1.2.2
• 1.2.3
• 1.2.4
• 1.2.5
• 1.2.6
• 1.2.7
• 1.2.8
• 1.2.9

Website

• Product: https://github.com/pavel-odintsov/fastnetmon/

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