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

High severity GitHub Reviewed Published Jun 8, 2026 in fission/fission • Updated Jul 28, 2026

Package

gomod github.com/fission/fission (Go)

Affected versions

<= 1.24.0

Patched versions

1.25.0

Description

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.

References

@sanketsudake sanketsudake published to fission/fission Jun 8, 2026
Published by the National Vulnerability Database Jun 10, 2026
Published to the GitHub Advisory Database Jul 28, 2026
Reviewed Jul 28, 2026
Last updated Jul 28, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(22nd percentile)

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

CVE ID

CVE-2026-50567

GHSA ID

GHSA-q6vm-xqc9-v3ff

Source code

Credits

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