Summary 

The AWS Load Balancer Controller includes an optional, default-enabled feature that manages WAF WebACLs on Application Load Balancers (ALBs) on your behalf. In versions 2.8.1 and earlier, if the WebACL annotation [1] alb.ingress.kubernetes.io/wafv2-acl-arn or alb.ingress.kubernetes.io/waf-acl-id was absent on Ingresses, the controller would automatically disassociate any existing WebACL from the ALBs, including those associated by AWS Firewall Manager (FMS). Customers on impacted versions should upgrade to prevent this issue from occurring.

Impact 

WebACLs attached to ALBs managed by the AWS Load Balancer Controller through methods other than Ingress annotations may be automatically removed, leaving the ALBs unprotected by WebACL. 

Impacted versions: [>=2.0.0;<2.8.2] 

Patches 

We addressed this issue in version 2.8.2 [2] and recommend customers upgrade. Now, if the WebACL annotation is absent on Ingress objects, any existing WebACL on the ALB will remain intact instead of being removed. 

Workarounds 

If the previous behavior affected you, you can mitigate it by disabling the WebACL management feature using the --enable-waf and --enable-wafv2 command-line flags [3] 

References 

If you have any questions or comments about this advisory, we ask that you contact AWS/Amazon Security via our vulnerability reporting page [4] or directly via email to aws-security@amazon.com. Please do not create a public GitHub issue. 

[1] https://kubernetes-sigs.github.io/aws-load-balancer-controller/latest/guide/ingress/annotations/#addons 

[2] https://github.com/kubernetes-sigs/aws-load-balancer-controller/releases/tag/v2.8.2 

[3] https://kubernetes-sigs.github.io/aws-load-balancer-controller/latest/deploy/configurations/#waf-addons 

[4] Vulnerability reporting page: https://aws.amazon.com/security/vulnerability-reporting