# CVE-2026-48683: FastNetMon Community Edition out-of-bounds read in NetFlow v9 collector

Source: https://junglewise.ai/threats/cve-2026-48683-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-2026-48683 · Severity: info · CVSS 7.5 · Published 2026-05-26

FastNetMon Community Edition, a high-performance DDoS sensor and traffic analyzer, contains a flaw in how it processes NetFlow v9 network traffic data. An attacker can send specially crafted network packets that cause the software to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information from the system's memory or cause the monitoring service to crash, potentially blinding network administrators to ongoing DDoS attacks.

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-2026-48683 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-48683 being exploited in the wild.

**How severe is CVE-2026-48683?** 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-2026-48683?** 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-2026-48683 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-48683?** 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 vulnerability exists in `src/netflow_plugin/netflow_v9_collector.cpp` within the `process_netflow_v9_data_flowset` function. The 'Data' template branch fails to perform a per-iteration bounds check against the packet end pointer when iterating over flow records, unlike the 'Options' branch which correctly implements this check. Because NetFlow v9 is a template-based protocol sent over unauthenticated UDP, a remote attacker can provide a malicious template definition followed by a truncated data packet. This forces the parser to read past the UDP receive buffer and into adjacent heap memory. An attacker can potentially leak sensitive memory contents (such as BGP state or configuration data) if they can observe the collector's output, or cause a denial-of-service via a segmentation fault.

## Affected products

- FastNetMon LTD FastNetMon Community Edition through 1.2.9

## Timeline

- 2026-04-25: other: Vulnerability reported to vendor
- 2026-05-23: disclosed: Public disclosure by Lorikeet Security
- 2026-05-26: advisory: CVE published by MITRE/NVD

## 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-2026-48683-netflow-v9-data-oob](https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48683-netflow-v9-data-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 parser](https://junglewise.ai/threats/cve-2026-48684-fastnetmon-community-edition-out-of-bounds-read-in-netflow-v9)