Is CVE-2021-3773 in the CISA KEV catalog?

No. CVE-2021-3773 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-3773?

CVE-2021-3773 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2021-3773?

CVE-2021-3773 has an EPSS score of 5.28% (92th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-3773?

Upgrade linux kernel to 5.15.15 or later.

CVE & CISA-KEV Catalog

CVE-2021-3773

CRITICALEPSS 92th pctl

9.8

CVSS v3

NVD

Description

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

CWE-200Information Exposure

How to fix

Remediation Available

linux kernelNVD

Affected:>= 5.15, < 5.15.15Fixed in:5.15.15CVE-2021-3773derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

5.28%probability of exploitation in 30 days

92ndpercentile

High risk: more likely to be exploited than 92% of all known CVEs.

References

Patch1

oracle.com

Third-Party Advisory1

bugzilla.redhat.com

Other references2

Related Vulnerabilities

Other CWE-200 (Information Exposure) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-24919	High	8.6	100%	KEV + Ransom	-
CVE-2020-14181	Medium	5.3	100%	-	Fix
CVE-2021-34429	Medium	5.3	99%	-	Fix
CVE-2018-11409	Medium	5.3	98%	-	-
CVE-2021-41277	Critical	10.0	97%	KEV	-
CVE-2016-2183	High	7.5	96%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-03-28.