CVE-2021-3773

Name: CVE-2021-3773
Creator: NVD / NIST
Published: 2022-02-16T19:15:08.763+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 5.32%

Last modified Jun 17, 2026

CVE-2021-3773 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. A flaw in netfilter could allow a network-connected attacker to infer openvpn connection endpoint information for further use in traditional network attacks.. EPSS estimates a 5.32% chance of exploitation in the next 30 days.

Description

A flaw in netfilter could allow a network-connected attacker to infer openvpn connection endpoint information for further use in traditional network attacks.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

5.32%

91.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-200

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	< 5.14
Linux	Linux Kernel	>= 5.15, < 5.15.15
Fedoraproject	Fedora	34
Redhat	Enterprise Linux	6.0
Redhat	Enterprise Linux	7.0
Redhat	Enterprise Linux	8.0
Oracle	Communications Cloud Native Core Binding Support Function	22.1.3
Oracle	Communications Cloud Native Core Network Exposure Function	22.1.1
Oracle	Communications Cloud Native Core Policy	22.2.0

References

https://bugzilla.redhat.com/show_bug.cgi?id=2004949Issue Tracking, Third Party Advisory
https://citizenlab.ca/2024/07/vulnerabilities-in-vpns-paper-presented-at-the-privacy-enhancing-technologies-symposium-2024/
https://www.oracle.com/security-alerts/cpujul2022.htmlPatch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2004949Issue Tracking, Third Party Advisory
https://citizenlab.ca/2024/07/vulnerabilities-in-vpns-paper-presented-at-the-privacy-enhancing-technologies-symposium-2024/
https://security.netapp.com/advisory/ntap-20250328-0004/
https://www.oracle.com/security-alerts/cpujul2022.htmlPatch, Third Party Advisory

Timeline

Published: Feb 16, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is 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.

How severe is CVE-2021-3773?

CVE-2021-3773 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 5.32% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3773?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3773?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST