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fix feat TrustManager that accepts all certificates #4295

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fix feat TrustManager that accepts all certificates #4295

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odaysec
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@odaysec odaysec commented Sep 29, 2025

java/kubernetes/src/main/java/io/kubernetes/client/openapi/ApiClient.java

Lines 1499 to 1520 in c14bb93

trustManagers = new TrustManager[]{
new X509TrustManager() {
@Override
public void checkClientTrusted(java.security.cert.X509Certificate[] chain, String authType) throws CertificateException {
}
@Override
public void checkServerTrusted(java.security.cert.X509Certificate[] chain, String authType) throws CertificateException {
}
@Override
public java.security.cert.X509Certificate[] getAcceptedIssuers() {
return new java.security.cert.X509Certificate[]{};
}
}
};
hostnameVerifier = new HostnameVerifier() {
@Override
public boolean verify(String hostname, SSLSession session) {
return true;
}
};

To address this vulnerability, we must remove the custom TrustManager and HostnameVerifier that accept all certificates.

  • If the intention is to allow self-signed certificates in some cases, explicit trusted certificates should be loaded from a secure location into a KeyStore, as demonstrated in the good example in the background.
  • The TrustManager should be initialized via a TrustManagerFactory with a KeyStore containing only the explicitly trusted certificates.
  • Hostname verification should not be disabled; use the standard verifier unless on localhost for very specific reasons.
  • Changes are required within the applySslSettings() method:
    • Remove (or replace) the block starting on line 1498 that creates an insecure TrustManager and HostnameVerifier.
    • Instead, if verifyingSsl is false, throw an exception or require the user to provide a trusted CA cert, as in the else branch. This eliminates the insecure option entirely.

References

Security with HTTPS and SSL

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[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: odaysec
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@k8s-ci-robot k8s-ci-robot added the cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. label Sep 29, 2025
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Welcome @odaysec!

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@k8s-ci-robot k8s-ci-robot added the size/S Denotes a PR that changes 10-29 lines, ignoring generated files. label Sep 29, 2025
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@odaysec this code comes from the upstream code generator:

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache#L1779

If you want to make a change, that's the place to make it, but I suspect that it will not be accepted, as there are circumstances when people want to use self-signed certificates in testing and they need this capability.

But if you do get changes accepted upstream, we'll pick them up next time we regenerate.

I'm going to close this PR for now since we won't merge this one.

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@brendandburns brendandburns Awaiting requested review from brendandburns

@yue9944882 yue9944882 Awaiting requested review from yue9944882

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