CVE-2021-25735: kubernetes Incomplete Internal State Distinction
Vulnerability summary
CVE-2021-25735 is a medium (CVSS 6.5) Incomplete Internal State Distinction vulnerability in kubernetes. EPSS estimates a 5.38% chance of exploitation in the next 30 days, higher than 92.5% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 2 · Related 4Timeline
- 06-09-2021PublishedVulnerability first disclosed.
- 16-09-2024Last modifiedVulnerability information updated.
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.
CVSS metrics
8 scores · 7 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H
- OSV · WolfiEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H
- OSV · GoEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H
- OSV · ChainguardEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H
- NVDNIST6.5MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H
EPSS trend
Probability
5.38%
Chance of exploitation in the next 30 days
Percentile
93%
Versus all other CVEs
30-day change
-0.15 pp
From 5.52% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Chainguard1 product
- kubeflow-pipelinesAll versions (No fix recorded)
Debian1 product
- kubernetes< 1.20.5+really1.20.2-1
K8s.io1 product
- kubernetes≥ 1.19.0, < 1.19.10 | < 1.18.18 | ≥ 1.20.0, < 1.20.6
Kubernetes1 product
- kubernetes≥ unspecified, ≤ 1.18.17 | ≥ unspecified, ≤ 1.19.9 | ≥ unspecified, ≤ 1.20.5 | < 1.18.18 | ≥ 1.19.0, < 1.19.10 | ≥ 1.20.0, < 1.20.6
Ubuntu1 product
- kubernetesAll versions (No fix recorded)
Wolfi1 product
- kubeflow-pipelinesAll versions (No fix recorded)
6 vendors · 6 products
References
14 links- groups.google.com/g/kubernetes-security-announce/c/FKAGqT4jx9YX Refsource MISCAdvisoryWEBMailing ListThird Party Advisory
