Arch Linux Security Advisory ASA-202106-29 ========================================== Severity: Low Date : 2021-06-09 CVE-ID : CVE-2021-25737 Package : kube-apiserver Type : insufficient validation Remote : Yes Link : https://security.archlinux.org/AVG-1970 Summary ======= The package kube-apiserver before version 1.21.1-1 is vulnerable to insufficient validation. Resolution ========== Upgrade to 1.21.1-1. # pacman -Syu "kube-apiserver>=1.21.1-1" The problem has been fixed upstream in version 1.21.1. Workaround ========== To mitigate this vulnerability without upgrading kube-apiserver, you can create a validating admission webhook that prevents EndpointSlices with endpoint addresses in the 127.0.0.0/8 and 169.254.0.0/16 ranges. If you have an existing admission policy mechanism (like OPA Gatekeeper) you can create a policy that enforces this restriction. Description =========== A security issue was discovered in kube-apiserver before version 1.21.1 where a user may be able to redirect pod traffic to private networks on a node. Kubernetes already prevents creation of Endpoint IPs in the localhost or link-local range, but the same validation was not performed on EndpointSlice IPs. Impact ====== A user could redirect pod traffic to private networks on a node. References ========== https://github.com/kubernetes/kubernetes/issues/102106 https://github.com/kubernetes/kubernetes/pull/101084 https://github.com/kubernetes/kubernetes/commit/233c8d6eeef9e7a259c39dd1db09... https://security.archlinux.org/CVE-2021-25737