CVE-2025-9708

Kubernetes C# Client: improper certificate validation in custom CA mode may lead to man-in-the-middle attacks

Published Sep 16, 2025 CVSS 3.1 · 6.8 Medium EPSS < 1% KEV · Not listed
Description
A vulnerability exists in the Kubernetes C# client where the certificate validation logic accepts properly constructed certificates from any Certificate Authority (CA) without properly verifying the trust chain. This flaw allows a malicious actor to present a forged certificate and potentially intercept or manipulate communication with the Kubernetes API server, leading to possible man-in-the-middle attacks and API impersonation.

Remediation

Vendor Solution

Deploy the patch version of the Kubernetes C# client as soon as possible. Alternatively, move the CA certificates into the system trust store instead of specifying them in the kubeconfig file. Note: This approach may introduce new risks, as all processes on the system will begin to trust certificates signed by that CA. If you must use an affected version, you can disable custom CA and add the CA to the machine's trusted root.

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-29657 Kubernetes C# client accepts certificates from any CA without properly verifying the trust chain
Github GHSA Github GHSA GHSA-w7r3-mgwf-4mqq Kubernetes C# client accepts certificates from any CA without properly verifying the trust chain
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Kubernetes
Kubernetes kubernetes
Vendors & Products Kubernetes
Kubernetes kubernetes
Type Values Removed Values Added
Description A vulnerability exists in the Kubernetes C# client where the certificate validation logic accepts properly constructed certificates from any Certificate Authority (CA) without properly verifying the trust chain. This flaw allows a malicious actor to present a forged certificate and potentially intercept or manipulate communication with the Kubernetes API server, leading to possible man-in-the-middle attacks and API impersonation.
Title Kubernetes C# Client: improper certificate validation in custom CA mode may lead to man-in-the-middle attacks
Weaknesses CWE-295
References
Metrics cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
kubernetes
Published
Updated
Nov 4, 2025, 9:15 PM
Reserved
Aug 29, 2025, 4:21 PM
Status
Deferred
Published
Sep 16, 2025, 10:15 PM
Modified
Jun 17, 2026, 10:09 AM