Announcing Istio 1.8.6

This release fixes the security vulnerabilities described in our May 11th posts, ISTIO-SECURITY-2021-005 and ISTIO-SECURITY-2021-006.

Security update

• CVE-2021-31920: Istio contains a remotely exploitable vulnerability where an HTTP request path with multiple slashes or escaped slash characters (%2F or %5C) could potentially bypass an Istio authorization policy when path based authorization rules are used. See the ISTIO-SECURITY-2021-005 bulletin for more details.
  • CVSS Score: 8.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
• CVE-2021-29492: Envoy contains a remotely exploitable vulnerability where an HTTP request with escaped slash characters can bypass Envoy’s authorization mechanisms.
  • CVSS Score: 8.3 AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
• CVE-2021-31921: Istio contains a remotely exploitable vulnerability where an external client can access unexpected services in the cluster, bypassing authorization checks, when a gateway is configured with AUTO_PASSTHROUGH routing configuration. See the ISTIO-SECURITY-2021-006 bulletin for more details.
  • CVSS Score: 10.0 AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Changes

• Added security best practice for authorization policies

• Fixed istiod so it will no longer generate listeners for privileged gateway ports (<1024) if the gateway Pod does not have sufficient permissions. Issue 27566

• Fixed an issue where transport socket parameters are now taken into account when configured in EnvoyFilter. Issue 28996

• Fixed PeerAuthentication to not turn off mTLS while using multi-network, non-mTLS endpoints from the cross-network load-balancing endpoints to prevent 500 errors. Issue 28798

• Fixed a bug causing runaway logs in istiod after disabling the default ingress controller. Issue 31336

• Fixed the Kubernetes API server so it is now considered to be cluster-local by default . This means that any pod attempting to reach kubernetes.default.svc will always be directed to the in-cluster server. Issue 31340

• Fixed Istio operator to prune resources that do not belong to the specific Istio operator CR. Issue 30833

Breaking Changes

As part of the fixes for ISTIO-SECURITY-2021-006, the previously deprecated .global stub domain for multicluster will no longer work.

This change can be temporarily disabled if desired by setting the environment variable PILOT_ENABLE_LEGACY_AUTO_PASSTHROUGH=true in Istiod. However, this is strongly discouraged, as it negates the fix to ISTIO-SECURITY-2021-006.

Please follow the Multicluster Installation documentation for more information.