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PYSEC-2026-2861

PDM wheel installation leads to Path Traversal via overridden write_to_fs

Quick fix

PYSEC-2026-2861 — pdm: upgrade to the fixed version with the command below.

pip install --upgrade 'pdm>=2.27.0'

Details

InstallDestination.write_to_fs() in src/pdm/installers/installers.py overrides the base class to add symlink/hardlink support but replaces the safe _path_with_destdir() (which validates via Path.resolve() + is_relative_to()) with a bare os.path.join() that performs no path validation. A malicious wheel with traversal entries can write arbitrary files. Same class as Poetry CVE-2026-34591. Fix ready at: https://github.com/pdm-project/pdm/pull/3787.

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/pdm

Introduced in: 0Fixed in: 2.27.0

Fixpip install --upgrade 'pdm>=2.27.0'

References

https://github.com/pdm-project/pdm/security/advisories/GHSA-78v8-vpjp-cjqh[WEB]
https://github.com/pdm-project/pdm/pull/3787[WEB]
https://github.com/pdm-project/pdm[PACKAGE]
https://github.com/pdm-project/pdm/releases/tag/2.27.0[WEB]
https://pypi.org/project/pdm[PACKAGE]
https://github.com/advisories/GHSA-78v8-vpjp-cjqh[ADVISORY]
https://nvd.nist.gov/vuln/detail/CVE-2026-47764[ADVISORY]