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/<ns>/ directories, into mounted secret/config volumes, or into the fetcher's own binary.
Affected
Project: github.com/fission/fission
Versions: all up to and including v1.24.0
Audited commit: 647c141
Component: pkg/utils/zip.go (Unarchive)
Configuration: default; triggered when the fetcher downloads and extracts a zip archive
PR #3444 (commit 55704aca) — Unarchive now opens an os.Root on the destination, validates each
archive entry name (rejects absolute paths and .. traversal), and refuses symlink entries up front. The os.Root confines every mkdir / create to the destination in the kernel.
Regression coverage: TestUnarchiveZipSlip in pkg/utils/zip_test.go exercises parent-traversal, absolute-path, and symlink entries.