---
id: "CVE-2026-63121"
kind: "vulnerability"
aliases: ["CVE-2026-63121"]
title: "Kubewarden trusted-repos policy: mixed-case registry hostnames bypass reject lists"
severity: "medium"
cvss: 6.3
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["admission-control", "kubernetes", "kubewarden", "package"]
not_affected_if: ["allow-list-only", "policy-not-deployed"]
published_at: "2026-10-30T22:16:58+00:00"
first_seen_at: "2026-10-30T22:25:56+00:00"
updated_at: "2026-10-30T22:27:16+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63121", "first_seen_at": "2026-10-30T22:25:56+00:00"}]
---

# Kubewarden trusted-repos policy: mixed-case registry hostnames bypass reject lists

The trusted-repos-policy in Kubewarden policies compares image registry hostnames case-sensitively, though DNS names are case-insensitive. An image with an uppercase or mixed-case registry hostname can slip past a reject-list rule, so a prohibited image gets admitted to the cluster.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check whether the cluster runs the Kubewarden trusted-repos-policy with a reject list, for example in the `ClusterAdmissionPolicy` objects.
- Check the installed policy version against `2.1.2`.

## Fix

- Upgrade the Kubewarden policies to `2.1.2` or later.

## Timeline

- 2026-10-30T22:25:56+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-63121

## From the sources

Kubewarden policies is a collection of WebAssembly policies for securing and governing Kubernetes clusters. For versions provisionally classified as affected before 2.1.2, `trusted-repos-policy` compares an image's `registry` hostname against `reject lists` and `allow lists` case-sensitively even though `registry` DNS names are case-insensitive. An image with an uppercase or mixed-case `registry` hostname can miss a rejection rule for the equivalent lowercase host, so the admission policy accepts a resource whose container runtime pulls the same prohibited image. Only reject-list configurations have this bypass: allow-list configurations fail closed by over-denying differently cased hostnames. The security consequences depend on the configured rejection policy and deployment environment. This issue is fixed in version 2.1.2.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_