---
id: CVE-2026-25121
aliases:
  - GHSA-5g94-c2wx-8pxw
  - GO-2026-4405
title: >-
  apko has a path traversal in apko dirFS which allows filesystem writes outside
  base
summary: >-
  apko has a path traversal in apko dirFS which allows filesystem writes outside
  base
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'
vendor: apko
product: chainguard.dev/apko
ecosystem: go
affected:
  - 'chainguard.dev/apko >= 0.14.8, < 1.1.0'
patched:
  - chainguard.dev/apko 1.1.0
published: '2026-02-03'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:34.269342712Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-5g94-c2wx-8pxw'
references:
  - url: >-
      https://github.com/chainguard-dev/apko/security/advisories/GHSA-5g94-c2wx-8pxw
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-25121'
  - url: >-
      https://github.com/chainguard-dev/apko/commit/d8b7887a968a527791b3c591ae83928cb49a9f14
  - url: 'https://github.com/chainguard-dev/apko'
tags:
  - osv
  - go
epss: 0.00392
epssPercentile: 0.30545
ingestedAt: '2026-09-12T03:13:01.755Z'
---

## Overview

A Path Traversal vulnerability was discovered in apko's dirFS filesystem abstraction. An attacker who can supply a malicious APK package (e.g., via a compromised or typosquatted repository) could create directories or symlinks outside the intended installation root. The MkdirAll, Mkdir, and Symlink methods in pkg/apk/fs/rwosfs.go use filepath.Join() without validating that the resulting path stays within the base directory.

**Fix:** Fixed by [d8b7887](https://github.com/chainguard-dev/apko/commit/d8b7887a968a527791b3c591ae83928cb49a9f14). Merged into release. 

**Acknowledgements**                                                                                                                                                                        
                                                                                                                                                                                              
apko thanks Oleh Konko from [1seal](https://1seal.org/) for discovering and reporting this issue.

## Affected packages

- `chainguard.dev/apko >= 0.14.8, < 1.1.0`

## Remediation

Upgrade to a patched release:

- `chainguard.dev/apko 1.1.0`