Home/CVE/Kube-proxy on Windows can unintentionally forward traffic to local processes listening on the same port (“spec.ports
CVE

CVE-2021-25736

Kube-proxy on Windows can unintentionally forward traffic to local processes listening on the same port (“spec.ports

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.

MEDIUM · CVSS 5.8 EPSS 0.00091
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules15 YARA rules0
⬡

Weakness Classification

CWE-114Process Control
▤

Affected Products & Versions

3
kubernetes>= 1.18.0 and < 1.18.18
kubernetes>= 1.19.0 and < 1.19.10
kubernetes>= 1.20.0 and < 1.20.6
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Go k8s.io/kubernetes MODERATE fixed in 1.21
◈

Sigma Hunt Rules

15
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productmediumKubernetes Events Deleted
productmediumKubernetes Admission Controller Modification
productmediumKubernetes CronJob/Job Modification
productmediumKubernetes Potential Enumeration Activity
productmediumKubernetes Secrets Modified or Deleted
productmediumKubernetes Rolebinding Modification
▣

Scoring & Timeline

5.8
MEDIUM · CVSS v3.1 · jordan@liggitt.net
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD30 Oct 2023 · 03:15 AM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:N/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

2
suse-csafopenSUSE-SU-2025:15424-1
rhsaRHSA-2021:2130Moderate
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/kubernetes/kubernetes/pull/99958Third Party Advisory
https://groups.google.com/g/kubernetes-security-announce/c/lIoOPObO51Q/m/O15LOazPAgAJMailing ListThird Party Advisory
https://security.netapp.com/advisory/ntap-20231221-0003/
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