CVE-2021-23018

Name: CVE-2021-23018
Creator: NVD / NIST
Published: 2021-06-01T12:15:07.72+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.4/10EPSS 0.54%

Last modified Jun 17, 2026

CVE-2021-23018 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. Intra-cluster communication does not use TLS. The services within the NGINX Controller 3.x before 3.4.0 namespace are using cleartext protocols inside the cluster.. EPSS estimates a 0.54% chance of exploitation in the next 30 days.

Description

Intra-cluster communication does not use TLS. The services within the NGINX Controller 3.x before 3.4.0 namespace are using cleartext protocols inside the cluster.

Metrics

CVSS 3.1

7.4/10

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

EPSS Probability

0.54%

41.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
F5	Nginx Controller	>= 3.0.0, <= 3.4.0

References

https://support.f5.com/csp/article/K97002210Vendor Advisory
https://support.f5.com/csp/article/K97002210Vendor Advisory

Timeline

Published: Jun 1, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-23018?

Intra-cluster communication does not use TLS. The services within the NGINX Controller 3.x before 3.4.0 namespace are using cleartext protocols inside the cluster.

How severe is CVE-2021-23018?

CVE-2021-23018 has a CVSS score of 7.4/10 (HIGH severity). The EPSS model estimates a 0.54% probability of exploitation in the next 30 days.

How do I fix CVE-2021-23018?

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-2021-23018?

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

Scan your code now

Source: NVD / NIST