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[kubernetes] CVE-2021-25735: Validating Admission Webhook does not observe some previous fields
From: Tim Allclair <timallclair () gmail com>
Date: Wed, 14 Apr 2021 09:06:02 -0700
A security issue was discovered in kube-apiserver that could allow node updates to bypass a Validating Admission Webhook. You are only affected by this vulnerability if you run a Validating Admission Webhook for Nodes that denies admission based at least partially on the old state of the Node object. This issue has been rated Medium ( CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H <https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H>), and assigned CVE-2021-25735. Note: This only impacts validating admission plugins that rely on old values in certain fields, and does not impact calls from kubelets that go through the built-in NodeRestriction admission plugin. Affected Versions - kube-apiserver v1.20.0 - v1.20.5 - kube-apiserver v1.19.0 - v1.19.9 - kube-apiserver <= v1.18.17 Fixed Versions This issue is fixed in the following versions: - kube-apiserver v1.21.0 - kube-apiserver v1.20.6 - kube-apiserver v1.19.10 - kube-apiserver v1.18.18 Detection If you find evidence that this vulnerability has been exploited, please contact security () kubernetes io Additional Details See Kubernetes Issue #100096 <https://github.com/kubernetes/kubernetes/issues/100096> for more details. Acknowledgements This vulnerability was reported by Rogerio Bastos & Ari Lima from RedHat Thank You, Tim Allclair on behalf of the Kubernetes Product Security Committee
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- [kubernetes] CVE-2021-25735: Validating Admission Webhook does not observe some previous fields Tim Allclair (Apr 14)