CVE-2021-25736

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.

Published: Oct 30, 2023
Updated: May 4, 2025
CVE: CVE-2021-25736
GHSA: GHSA-35c7-w35f-xwgh
Severity: Medium
Exploit:

CVSS v3:

Severity: Medium
Score: 6.3
AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

No CWE or OWASP classifications available.

Affected Software
References

Software	From	Fixed in
k8s.io/kubernetes	-	1.21
kubernetes / kubernetes	1.18.0	1.18.18
kubernetes / kubernetes	1.19.0	1.19.10
kubernetes / kubernetes	1.20.0	1.20.6

https://github.com/kubernetes/kubernetes/commit/b014610de3e5cf1bb0f7844b5758d29fc18b75e6
https://github.com/kubernetes/kubernetes/pull/99958
https://groups.google.com/g/kubernetes-security-announce/c/lIoOPObO51Q/m/O15LOazPAgAJ
https://security.netapp.com/advisory/ntap-20231221-0003/

Vulnerability Database

CVE-2021-25736

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