How severe is CVE-2021-23018?

CVE-2021-23018 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2021-23018 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-23018?

CVE-2021-23018 affects F5 Nginx Controller. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-23018?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-23018 published?

CVE-2021-23018 was published on 2021-06-01 and last updated on 2026-06-17.

CVE-2021-23018

CVE-2021-23018 is a high-severity vulnerability in F5 Nginx Controller with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-319.

Key facts

Severity: High (CVSS 3.x base score 7.4)
CVSS v2: 5.8
EPSS exploit prediction: 1% (42nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-319
Affected product: F5 Nginx Controller
Published: 2021-06-01
Last modified: 2026-06-17

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.

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 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2021-23018 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-23018?: CVE-2021-23018 affects F5 Nginx Controller. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-23018?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-23018 published?: CVE-2021-23018 was published on 2021-06-01 and last updated on 2026-06-17.

References

https://support.f5.com/csp/article/K97002210

Affected products (1)

cpe:2.3:a:f5:nginx_controller:*:*:*:*:*:*:*:*

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