# CVE-2026-93424: FastNetMon heap-use-after-free in NetFlow/IPFIX template cache

Source: https://junglewise.ai/threats/cve-2026-93424-fastnetmon-is-a-high-performance-ddos-detector-and-sensor-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-05. Updated: 2026-11-05  
License: CC BY 4.0 with a link back

CVE-2026-93424 · Severity: high · CVSS 7.5 · Published 2026-11-05

FastNetMon is a high-performance DDoS detection system that processes network flow data from multiple sources. A flaw in its NetFlow/IPFIX template caching mechanism allows an unauthenticated attacker sending specially crafted packets to both listener ports to trigger a heap-use-after-free condition, reliably crashing the FastNetMon process and disrupting DDoS protection. On deployments with multiple NetFlow listener ports (a standard configuration), this can be exploited within seconds.

Technologies: [Pavel-Odintsov Fastnetmon](https://junglewise.ai/threats/technologies/fastnetmon). Vendors: [Pavel-Odintsov](https://junglewise.ai/threats/vendors/pavel-odintsov).

## Quick answers

**Is CVE-2026-93424 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-93424 being exploited in the wild.

**How severe is CVE-2026-93424?** High severity, with a CVSS score of 7.5, published 5 November 2026.

**Which products and versions are affected?** Pavel-Odintsov Fastnetmon 1.2.9 and earlier.

**Is there a fix for CVE-2026-93424?** 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-2026-93424 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-93424?** Check whether you run Pavel-Odintsov Fastnetmon 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

The vulnerability is a heap-use-after-free in peer_find_template() in the NetFlow v9/IPFIX collector modules. The function returns a pointer into the global template cache after releasing the mutex protecting it, but callers dereference this pointer (specifically the records vector) without holding a lock. On multi-port deployments, concurrent threads racing between add_update_peer_template() reassigning and reallocating template records and netflow9_flowset_to_store() reading those records triggers the use-after-free. An unauthenticated remote attacker on the network path can craft NetFlow packets with matching template IDs and source IDs across two listener ports to reliably trigger the crash.

## Affected products

- Pavel Odintsov FastNetMon 1.2.9 and earlier

## Timeline

- 2026-11-05: disclosed

## References

- [https://github.com/pavel-odintsov/fastnetmon/commit/a24e528d145b5371a7ab0bcdde23e4b4b99506e9](https://github.com/pavel-odintsov/fastnetmon/commit/a24e528d145b5371a7ab0bcdde23e4b4b99506e9)
- [https://github.com/pavel-odintsov/fastnetmon/security/advisories/GHSA-ph88-95vc-x6gv](https://github.com/pavel-odintsov/fastnetmon/security/advisories/GHSA-ph88-95vc-x6gv)

## Related threats

- [FastNetMon out-of-bounds read in sFlow parser](https://junglewise.ai/threats/cve-2026-92698-fastnetmon-is-a-high-performance-ddos-detector-and-sensor-in)
- [FastNetMon out-of-bounds read in pcap packet parser](https://junglewise.ai/threats/cve-2026-92695-fastnetmon-is-a-high-performance-ddos-detector-and-sensor-in)