CVE-2019-11254: Kubernetes: denial of service vulnerability from malicious YAML payloads

[CJ Cullen <cjcullen () google com>]

Hello Kubernetes Community,



A denial of service vulnerability in the Kubernetes API Server was
discovered and assigned CVE-2019-11254. This vulnerability has been given
an initial severity of Medium (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
<https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H>.
Details are below and at https://issue.k8s.io/89535



The following versions including the fix have been released:

   -

   v1.15.10 <https://github.com/kubernetes/kubernetes/releases/tag/v1.15.10>
   -

   v1.16.7 <https://github.com/kubernetes/kubernetes/releases/tag/v1.16.7>
   -

   v1.17.3 <https://github.com/kubernetes/kubernetes/releases/tag/v1.17.3>



Details

CVE-2019-11254 is a denial of service vulnerability in the kube-apiserver,
allowing authorized users sending malicious YAML payloads to cause
kube-apiserver to consume excessive CPU cycles while parsing YAML.



The issue was discovered
<https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=18496> via the fuzz
test kubernetes/kubernetes#83750
<https://github.com/kubernetes/kubernetes/pull/83750>.



Affected components:

Kubernetes API server



Affected versions:

   -

   <= v1.15.9
   -

   v1.16.0-v1.16.6
   -

   v1.17.0-v1.17.2

How do I mitigate this vulnerability?

Prior to upgrading, these vulnerabilities can be mitigated by preventing
unauthenticated or unauthorized access to kube-apiserver.



Acknowledgements



Thanks to Mark Wolters from Google for writing the fuzz tests
<http://kubernetes/kubernetes#83750>, and to oss-fuzz
<https://github.com/google/oss-fuzz> for the support.



Thanks to Mike Danese from Google for reporting this issue
<https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=18496>.



- CJ Cullen on behalf of the Kubernetes Product Security Team