CVE-2021-3773
A flaw in netfilter could allow a network-connected attacker to infer openvpn connection endpoint information for further use in traditional network attacks.
- Published
- Feb 16, 2022
- Updated
- Mar 28, 2025
- Assigning CNA
- redhat
- Evidence observed
- Aug 8, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HLow · next 30 days
- Percentile
- 92.2%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
A flaw in netfilter could allow a network-connected attacker to infer openvpn connection endpoint information for further use in traditional network attacks.
Sources
1- CVE-2021-3773Exploit
Exploit script for CVE-2021-3773 (Port Shadow) targeting OpenVPN servers using Netfilter NAT. Performs deanonymization and man-in-the-middle attacks with concurrent scanning and stealth techniques.
Responsible use
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