Use-after-free in FastNetMon - #VU138933
Published: July 21, 2026
Vulnerability identifier: #VU138933
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to use-after-free in the NetFlow/IPFIX template cache when processing UDP flow data across multiple configured NetFlow/IPFIX listener ports. A remote attacker can send crafted NetFlow v9/IPFIX template redefinition and data packets to cause a denial of service.
Only deployments with more than one configured NetFlow/IPFIX listener port are vulnerable.
Affected software
FastNetMon
Remediation
Cybersecurity Help is not aware of any official solution to address this vulnerability.