CVE-2021-38209

Name: CVE-2021-38209
Creator: NVD / NIST
Published: 2021-08-08T20:15:07.423+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

LOWCVSS 3.3/10EPSS 0.28%

Last modified Jun 17, 2026

CVE-2021-38209 is a low-severity vulnerability rated 3.3/10 on the CVSS scale. net/netfilter/nf_conntrack_standalone.c in the Linux kernel before 5.12.2 allows observation of changes in any net namespace because these changes are leaked into all other net namespaces. This is related to the NF_SYSCTL_CT_MAX, NF_SYSCTL_CT_EXPECT_MAX, and NF_SYSCTL_CT_BUCKETS sysctls.. EPSS estimates a 0.28% chance of exploitation in the next 30 days.

Description

net/netfilter/nf_conntrack_standalone.c in the Linux kernel before 5.12.2 allows observation of changes in any net namespace because these changes are leaked into all other net namespaces. This is related to the NF_SYSCTL_CT_MAX, NF_SYSCTL_CT_EXPECT_MAX, and NF_SYSCTL_CT_BUCKETS sysctls.

Metrics

CVSS 3.1

3.3/10

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

EPSS Probability

0.28%

20.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-203

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	< 5.12.2

References

https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.2Mailing List, Patch, Vendor Advisory
https://github.com/torvalds/linux/commit/2671fa4dc0109d3fb581bc3078fdf17b5d9080f6Patch, Third Party Advisory
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.2Mailing List, Patch, Vendor Advisory
https://github.com/torvalds/linux/commit/2671fa4dc0109d3fb581bc3078fdf17b5d9080f6Patch, Third Party Advisory

Timeline

Published: Aug 8, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-38209?

How severe is CVE-2021-38209?

CVE-2021-38209 has a CVSS score of 3.3/10 (LOW severity). The EPSS model estimates a 0.28% probability of exploitation in the next 30 days.

How do I fix CVE-2021-38209?

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-2021-38209?

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

Scan your code now

Source: NVD / NIST