CVE-2021-25737 log

Source
Severity Low
Remote Yes
Type Insufficient validation
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.
Group Package Affected Fixed Severity Status Ticket
AVG-1970 kube-apiserver 1.21.0-1 1.21.1-1 Low Fixed
Date Advisory Group Package Severity Type
09 Jun 2021 ASA-202106-29 AVG-1970 kube-apiserver Low insufficient validation
References
https://github.com/kubernetes/kubernetes/issues/102106
https://github.com/kubernetes/kubernetes/pull/101084
https://github.com/kubernetes/kubernetes/commit/233c8d6eeef9e7a259c39dd1db096479044820ae
Notes
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.