CVE-2021-25735

Publication date 6 September 2021

Last updated 11 July 2025

Ubuntu priority

Cvss 3 Severity Score

Description

A security issue was discovered in kube-apiserver that could allow node updates to bypass a Validating Admission Webhook. Clusters are only affected by this vulnerability if they run a Validating Admission Webhook for Nodes that denies admission based at least partially on the old state of the Node object. Validating Admission Webhook does not observe some previous fields.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
kubernetes	25.04 plucky	Not in release
	24.10 oracular	Ignored end of life, was needs-triage
	24.04 LTS noble	Not affected
	23.10 mantic	Ignored end of life, was needs-triage
	23.04 lunar	Ignored end of life, was needs-triage
	22.10 kinetic	Ignored end of life, was needs-triage
	22.04 LTS jammy	Not affected
	21.10 impish	Ignored end of life
	21.04 hirsute	Ignored end of life
	20.10 groovy	Ignored end of life
	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	6.5 · Medium
Attack vector	Network
Attack complexity	Low
Privileges required	High
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	High
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H