# CVE-2026-48684: FastNetMon Community Edition out-of-bounds read in NetFlow v9 parser

Source: https://junglewise.ai/threats/cve-2026-48684-fastnetmon-community-edition-out-of-bounds-read-in-netflow-v9  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-26. Updated: 2026-05-26  
License: CC BY 4.0 with a link back

CVE-2026-48684 · Severity: info · CVSS 7.5 · Published 2026-05-26

FastNetMon Community Edition, a high-performance DDoS sensor used to monitor network traffic, contains a vulnerability in how it processes NetFlow v9 metadata. An attacker can send a specially crafted network packet that causes the software to read memory outside of its intended boundaries. This can lead to a service outage (denial of service) by crashing the monitoring daemon or potentially allow an attacker to view sensitive information stored in the system's memory.

Technologies: [FastNetMon LTD FastNetMon Community Edition](https://junglewise.ai/threats/technologies/fastnetmon-community-edition). Vendors: [FastNetMon LTD](https://junglewise.ai/threats/vendors/fastnetmon-ltd).

## Quick answers

**Is CVE-2026-48684 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-48684 being exploited in the wild.

**How severe is CVE-2026-48684?** Informational severity, with a CVSS score of 7.5, published 26 May 2026.

**Which products and versions are affected?** FastNetMon LTD FastNetMon Community Edition through 1.2.9.

**Is there a fix for CVE-2026-48684?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-48684 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-48684?** Check whether you run FastNetMon LTD FastNetMon Community Edition at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds read exists in the process_netflow_v9_options_template() function within src/netflow_plugin/netflow_v9_collector.cpp. The vulnerability is caused by a lack of bounds checking in two loops (scope parsing and options parsing) that iterate based on attacker-controlled length fields (option_scope_length and option_length). An attacker can provide inflated length values that cause the parser to read past the end of the UDP packet buffer. Additionally, a lack of alignment validation can cause misaligned reads, leading to crashes on certain architectures. This is a single-packet, unauthenticated attack reachable via the default NetFlow port (UDP 2055).

## Affected products

- FastNetMon LTD FastNetMon Community Edition through 1.2.9

## Timeline

- 2026-04-25: disclosed: Lorikeet Security notified FastNetMon LTD
- 2026-05-26: advisory: CVE-2026-48684 published by NVD/MITRE

## References

- [https://github.com/pavel-odintsov/fastnetmon](https://github.com/pavel-odintsov/fastnetmon)
- [https://github.com/pavel-odintsov/fastnetmon/blob/master/src/netflow_plugin/netflow_v9_collector.cpp](https://github.com/pavel-odintsov/fastnetmon/blob/master/src/netflow_plugin/netflow_v9_collector.cpp)
- [https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48684-netflow-v9-options-oob](https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48684-netflow-v9-options-oob)

## Related threats

- [FastNetMon Community Edition configuration injection in Juniper plugin](https://junglewise.ai/threats/cve-2026-48694-fastnetmon-community-edition-configuration-injection-in-juniper)
- [FastNetMon Community Edition improper TLS certificate validation in telemetry](https://junglewise.ai/threats/cve-2026-48697-fastnetmon-community-edition-improper-tls-certificate-validation)
- [FastNetMon Community Edition heap overflow in BGP AS_PATH encoder](https://junglewise.ai/threats/cve-2026-48691-fastnetmon-community-edition-heap-overflow-in-bgp-as-path-encoder)
- [FastNetMon Community Edition heap overflow in packet capture buffer](https://junglewise.ai/threats/cve-2026-48690-fastnetmon-community-edition-heap-overflow-in-packet-capture)
- [FastNetMon Community Edition out-of-bounds read in NetFlow v9 collector](https://junglewise.ai/threats/cve-2026-48683-fastnetmon-community-edition-out-of-bounds-read-in-netflow-v9)