Fission: Zip Slip in pkg/utils/zip.go:Unarchive allows fetcher to write outside the destination directory

CVE-2026-50567

What is CVE-2026-50567?

Fission is an open-source, Kubernetes-native serverless framework that simplifies the deployment of functions and applications on Kubernetes. Prior to version 1.25.0, Unarchive in pkg/utils/zip.go joined each archive entry name with the destination directory via filepath.Join and wrote the result without checking whether the resolved path stayed under the destination. A zip entry named ../../tmp/evil therefore landed at /tmp/evil. An attacker who could control a Package.Spec.Source.URL or Deployment.URL archive could induce the fetcher (running as the per-environment pod's fission-fetcher sidecar) to write files anywhere that process could reach: into other tenants' /packages// directories, into mounted secret/config volumes, or into the fetcher's own binary. This issue has been patched in version 1.25.0.

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