How severe is CVE-2021-23020?

CVE-2021-23020 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-23020 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-23020?

CVE-2021-23020 affects F5 Nginx Controller. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-23020?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-23020 published?

CVE-2021-23020 was published on 2021-06-01 and last updated on 2026-06-17.

CVE-2021-23020

CVE-2021-23020 is a medium-severity vulnerability in F5 Nginx Controller with a CVSS 3.x base score of 5.5. 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-330.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 2.1
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-330
Affected product: F5 Nginx Controller
Published: 2021-06-01
Last modified: 2026-06-17

Description

The NAAS 3.x before 3.10.0 API keys were generated using an insecure pseudo-random string and hashing algorithm which could lead to predictable keys.

Frequently asked questions

What is CVE-2021-23020?: The NAAS 3.x before 3.10.0 API keys were generated using an insecure pseudo-random string and hashing algorithm which could lead to predictable keys.
How severe is CVE-2021-23020?: CVE-2021-23020 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-23020 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-23020?: CVE-2021-23020 affects F5 Nginx Controller. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-23020?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-23020 published?: CVE-2021-23020 was published on 2021-06-01 and last updated on 2026-06-17.

References

https://support.f5.com/csp/article/K45263486

Affected products (1)

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

More vulnerabilities in F5 Nginx Controller

CVE-2020-27730 — Critical (CVSS 9.8): In versions 3.0.0-3.9.0, 2.0.0-2.9.0, and 1.0.1, the NGINX Controller Agent does not use absolute paths when calling…
CVE-2020-5901 — Critical (CVSS 9.6): In NGINX Controller 3.3.0-3.4.0, undisclosed API endpoints may allow for a reflected Cross Site Scripting (XSS) attack.…
CVE-2020-5900 — High (CVSS 8.8): In versions 3.0.0-3.4.0, 2.0.0-2.9.0, and 1.0.1, there is insufficient cross-site request forgery (CSRF) protections…
CVE-2020-5863 — High (CVSS 8.6): In NGINX Controller versions prior to 3.2.0, an unauthenticated attacker with network access to the Controller API can…
CVE-2020-5894 — High (CVSS 8.1): On versions 3.0.0-3.3.0, the NGINX Controller webserver does not invalidate the server-side session token after users…
CVE-2020-5867 — High (CVSS 8.1): In versions prior to 3.3.0, the NGINX Controller Agent installer script 'install.sh' uses HTTP instead of HTTPS to…

All CVEs affecting F5 Nginx Controller →

Other CWE-330 (Use of Insufficiently Random Values) vulnerabilities

CVE-2023-22601 — Critical (CVSS 10.0): InHand Networks InRouter 302, prior to version IR302 V3.5.56, and InRouter 615, prior to version…
CVE-2026-25072 — Critical (CVSS 9.8): XikeStor SKS8310-8X Network Switch firmware versions 1.04.B07 and prior contain a predictable session identifier…
CVE-2026-27755 — Critical (CVSS 9.8): SODOLA SL902-SWTGW124AS firmware versions through 200.1.20 contain a weak session identifier generation vulnerability…
CVE-2026-27637 — Critical (CVSS 9.8): FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to version 1.8.206,…
CVE-2025-64097 — Critical (CVSS 9.8): NervesHub is a web service that allows users to manage over-the-air (OTA) firmware updates of devices in the field. A…
CVE-2025-4607 — Critical (CVSS 9.8): The PSW Front-end Login & Registration plugin for WordPress is vulnerable to Privilege Escalation in all versions up…

Browse all CWE-330 (Use of Insufficiently Random Values) vulnerabilities →