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

Overview

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

Fix section (paste into the Fix / Patches field)

Fixed in v1.25.0 by:

• 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.

Affected packages

• github.com/fission/fission <= 1.24.0

Remediation

Upgrade to a patched release:

• github.com/fission/fission 1.25.0