CVE-2026-54247 Skipper: Unbounded Request Body Read in Admission Webhook Causes Memory Exhaustion DoS
An attacker with in-cluster access can cause memory exhaustion and process termination in Skipper by sending large request bodies to the admission webhook.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54247?
CVE-2026-54247 is a medium-severity denial of service vulnerability in zalando skipper, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-770
Which versions are affected by CVE-2026-54247?
3 open source packages ship an affected version, including github.com/zalando/skipper.
| Package | Affected | Fixed in |
|---|---|---|
github.com/zalando/skipper Go | All versions | 0.26.22 |
github.com/zalando/skipper Go | All versions | 0.26.22 |
github.com/zalando/skipper Go | All versions | 0.26.22 |
How do I fix CVE-2026-54247?
Upgrade github.com/zalando/skipper to 0.26.22 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-54247 being exploited?
There is no known exploitation of CVE-2026-54247 in the wild and no public exploit code.
Sources
Also known as GHSA-cwxq-rc9x-2jvv, GO-2026-6015.