CVE-2021-25736

Name: CVE-2021-25736
Creator: NVD / NIST
Published: 2023-10-30T03:15:07.653+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.3/10EPSS 0.91%

Last modified Jun 17, 2026

CVE-2021-25736 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. Kube-proxy on Windows can unintentionally forward traffic to local processes listening on the same port (“spec.ports[*].port”) as a LoadBalancer Service when the LoadBalancer controller does not set the “status.loadBalancer.ingress[].ip” field. Clusters where the LoadBalancer controller sets the “status.loadBalancer.ingress[].ip” field are unaffected.. EPSS estimates a 0.91% chance of exploitation in the next 30 days.

Description

Kube-proxy on Windows can unintentionally forward traffic to local processes listening on the same port (“spec.ports[*].port”) as a LoadBalancer Service when the LoadBalancer controller does not set the “status.loadBalancer.ingress[].ip” field. Clusters where the LoadBalancer controller sets the “status.loadBalancer.ingress[].ip” field are unaffected.

Metrics

CVSS 3.1

6.3/10

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

EPSS Probability

0.91%

55.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-114

Affected Software

Vendor	Product	Versions
Kubernetes	Kubernetes	>= 1.18.0, < 1.18.18
Kubernetes	Kubernetes	>= 1.19.0, < 1.19.10
Kubernetes	Kubernetes	>= 1.20.0, < 1.20.6

References

https://github.com/kubernetes/kubernetes/pull/99958Third Party Advisory
https://groups.google.com/g/kubernetes-security-announce/c/lIoOPObO51Q/m/O15LOazPAgAJMailing List, Third Party Advisory
https://security.netapp.com/advisory/ntap-20231221-0003/
https://github.com/kubernetes/kubernetes/pull/99958Third Party Advisory
https://groups.google.com/g/kubernetes-security-announce/c/lIoOPObO51Q/m/O15LOazPAgAJMailing List, Third Party Advisory
https://security.netapp.com/advisory/ntap-20231221-0003/

Timeline

Published: Oct 30, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-25736?

How severe is CVE-2021-25736?

CVE-2021-25736 has a CVSS score of 6.3/10 (MEDIUM severity). The EPSS model estimates a 0.91% probability of exploitation in the next 30 days.

How do I fix CVE-2021-25736?

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-2021-25736?

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

Scan your code now

Source: NVD / NIST