CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-93424
High (7.5) in pavel-odintsov fastnetmon. EPSS 0.3% estimated probability of exploitation activity in the next 30 days.
On this page
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.
Severity
- EPSS
- 0.3% estimated probability of exploitation activity in the next 30 days; 20th percentile. Scored 2026-11-10. A forecast for this CVE across the internet, not for your own systems.
- CWE
- CWE-416 Use After Free
- Published
- Modified
- NVD analysis
- Deferred: the NVD does not plan to analyze it
- Record from
- the NVD, synced
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Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| pavel-odintsov fastnetmon | <= 1.2.9 |
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Debian | 12, 13, 14 | fastnetmon | no fix listed | DEBIAN-CVE-2026-93424 |
| Ubuntu | 18.04:LTS, 26.10, Pro:20.04:LTS and 2 more | fastnetmon | no fix listed | UBUNTU-CVE-2026-93424 |
From the distributions' data via OSV.dev: the Debian Security Tracker; Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian · Ubuntu.
Red Hat
Red Hat rates this Important.
This vulnerability is rated as Important severity because unauthenticated remote attackers capable of reaching the collector listener ports can crash the monitoring service without requiring privileges, disrupting denial-of-service detection across the network. In typical Red Hat Enterprise Linux environments, FastNetMon is not included in standard package repositories and monitoring collectors are intended to reside on restricted management segments. The issue is further constrained to configurations defining multiple listening ports where parallel flow processing can trigger memory corruption. Neither data integrity nor system confidentiality is compromised, as the flaw exclusively causes daemon termination.
Restrict network access to the NetFlow and IPFIX collector ports to only trusted flow exporters, or configure FastNetMon to listen on a single port.
1. Restrict incoming traffic on the collector UDP port using firewalld to authorized exporter IP addresses:
```
firewall-cmd --permanent --zone=public --add-rich-rule='rule family="ipv4" source address="<trusted_router_ip>" port port="<collector_port>" protocol="udp" accept'
firewall-cmd --reload
```
2. Alternatively, adjust `/etc/fastnetmon.conf` to declare only a single listening port in `netflow_ports` rather than multiple ports, and restart the daemon:
```
systemctl restart fastnetmon
```
Caveats: Limiting ingress packets to explicit IP addresses requires defining all flow-exporting network devices. Restricting the configuration to a single port may constrain environments relying on multi-port flow ingestion.
Warning: Executing `firewall-cmd --reload` reloads active firewall rules. Restarting the service via `systemctl restart fastnetmon` will temporarily interrupt traffic flow processing.
Contains Red Hat Security Data © Red Hat, Inc., licensed under CC BY 4.0. Source: https://access.redhat.com/security/data. Modified: reformatted. Red Hat's page for CVE-2026-93424.