Kubewarden trusted-repos-policy: uppercase registry host bypasses registry/image deny rules
Only affects the trusted-repos-policy configured with reject lists, when an image uses an uppercase registry host. Fixed in Kubewarden policies 2.1.2.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 2.1.2
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The Kubewarden trusted-repos-policy, a WebAssembly policy used to govern Kubernetes clusters, is affected. When its reject-list rules are configured, an image whose registry hostname uses uppercase or mixed-case letters can slip past the rule that should block the lowercase equivalent, allowing a prohibited image to be admitted and pulled.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
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.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- kubewarden policies
fixed in 2.1.2
References 3
GitHub · kubewarden/policies
Questions about CVE-2026-63121
What does this mean?
The policy compares registry hostnames to its reject entries without normalizing case. An image with an uppercase or mixed-case host can match a reject entry written in lowercase without being caught, so the policy admits a resource whose container runtime then pulls an image the reject list prohibits.Source: github.com
Am I affected, and how do I check?
Kubewarden policies versions before 2.1.2 are affected, and only when trusted-repos-policy uses reject (deny) lists; allow-list configurations are not affected. To check, look at the policy version deployed and at whether its settings use a reject list.Source: github.com
What should I do about it?
Upgrade the Kubewarden policies to version 2.1.2 or later, which normalizes domain names to lowercase before matching rules. If an upgrade is not yet possible, a mutating admission webhook that normalizes the container image string is a workaround.Source: github.com
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data