CVE-2021-25736

Publication date 30 October 2023

Last updated 4 August 2025

Ubuntu priority

Cvss 3 Severity Score

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
kubernetes	21.04 hirsute	Not affected
	20.10 groovy	Not affected
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release

Notes

leosilva

kubernates is in fact a kubernetes installer that calls snap, not the package it self.

Severity score breakdown

Parameter	Value
Base score	6.3 · Medium
Attack vector	Network
Attack complexity	High
Privileges required	Low
User interaction	None
Scope	Changed
Confidentiality	High
Integrity impact	None
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

References

Other references

https://www.cve.org/CVERecord?id=CVE-2021-25736