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Date: Fri, 22 Apr 2022 09:37:42 -0700
From: CJ Cullen <>
Subject: [kubernetes] CVE-2021-25746: Ingress-nginx directive injection via annotations

Issue Details

A security issue was discovered in ingress-nginx
<> where a user that can create
or update ingress objects can use `.metadata.annotations` in an Ingress
object (in the `` or `extensions` API group) to obtain the
credentials of the ingress-nginx controller. In the default configuration,
that credential has access to all secrets in the cluster.

This issue has been rated High (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
and assigned CVE-2021-25746.
Affected Components and Configurations

This bug affects ingress-nginx. If you do not have ingress-nginx installed
on your cluster, you are not affected. You can check this by running
`kubectl get po -n ingress-nginx`.

Multitenant environments where non-admin users have permissions to create
Ingress objects are most affected by this issue.
Affected Versions



Fixed Versions





If you are unable to roll out the fix, this vulnerability can be mitigated
by implementing an admission policy that restricts the
`metadata.annotations` values to known safe (see the newly added rules
or the suggested value for annotation-value-word-blocklist

If you find evidence that this vulnerability has been exploited, please
Additional Details

See ingress-nginx Issue #8503
<> for more details.

This vulnerability was reported by Anthony Weems, and separately by

Thank You,

CJ Cullen on behalf of the Kubernetes Security Response Committee

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