Zalando Skipper up to 0.26.21 Kubernetes Admission admission.go io.ReadAll allocation of resources

Summaryinfo

A vulnerability, which was classified as problematic, was found in Zalando Skipper up to 0.26.21. This impacts the function io.ReadAll of the file dataclients/kubernetes/admission/admission.go of the component Kubernetes Admission. Executing a manipulation can lead to allocation of resources. This vulnerability is registered as CVE-2026-54247. It is possible to launch the attack remotely. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Zalando Skipper up to 0.26.21. It has been declared as problematic. This vulnerability affects the function io.ReadAll of the file dataclients/kubernetes/admission/admission.go of the component Kubernetes Admission. The manipulation with an unknown input leads to a allocation of resources vulnerability. The CWE definition for the vulnerability is CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. As an impact it is known to affect availability. CVE summarizes:

Skipper is an HTTP router and reverse proxy for service composition. Prior to 0.26.22, Handler in dataclients/kubernetes/admission/admission.go passes the body of requests to the Kubernetes admission endpoint at :9443/admission directly to io.ReadAll(r.Body) without a size limit. An attacker with in-cluster network access and a valid Kubernetes client certificate can send a very large body that causes unbounded memory allocation and an out-of-memory termination of the Skipper process. The disruption is limited to Ingress and RouteGroup admission rather than pod creation or unrelated admission controllers, and Kubernetes normally restarts the process. This issue is fixed in version 0.26.22.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-54247 since 06/12/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 0.26.22 eliminates this vulnerability.

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Productinfo

Vendor

• Zalando

Name

• Skipper

Version

• 0.26.0
• 0.26.1
• 0.26.2
• 0.26.3
• 0.26.4
• 0.26.5
• 0.26.6
• 0.26.7
• 0.26.8
• 0.26.9
• 0.26.10
• 0.26.11
• 0.26.12
• 0.26.13
• 0.26.14
• 0.26.15
• 0.26.16
• 0.26.17
• 0.26.18
• 0.26.19
• 0.26.20
• 0.26.21

Website

• Product: https://github.com/zalando/skipper/

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