[python-build-tools-kit] dev-python/setuptools has security issues - CVE-2026-59890

Nobody has claimed this yet.

As reported by Docker Scout:

# CVE-2026-59890
## ADVISORY - github
### Summary

When building a source distribution (python -m build --sdist / setup.py sdist), setuptools' FileList applies MANIFEST.in directives (exclude, global-exclude, recursive-exclude, prune) by matching a compiled glob against on-disk file names byte-for-byte, with no Unicode normalization. On normalization-preserving filesystems (notably macOS APFS and HFS+), a file written in NFD and a MANIFEST.in rule written in NFC refer to the same file but are byte-distinct, so the exclusion silently fails to match. A file the maintainer intended to exclude is then packed into the .tar.gz and, if published, uploaded to the public, immutable PyPI index.

### Impact

MANIFEST.in exclusions are the documented mechanism maintainers use to keep secrets, local configs, and private fixtures out of the published sdist. A non-ASCII excluded file may be published to the public, immutable PyPI index despite the rule — an irreversible disclosure with no visual cue (NFC and NFD forms render identically). Exposure is filesystem-dependent and most relevant on macOS APFS/HFS+, where many maintainers build and publish. Pure-ASCII rules are unaffected.

### Remediation

Normalize both the walked path and each MANIFEST.in pattern to a single canonical form before matching, in both setuptools/command/egg_info.py (FileList) and the vendored setuptools/_distutils/filelist.py. For an exclusion list, err toward excluding more, and document that MANIFEST.in matching is normalization-insensitive on macOS.
Credit

Reported by Tomas Illuminati. Coordinated via CERT/CC VINCE VU#604762.

Affected Ranges: <83.0.0
Fixed versions: 83.0.0

Start by reviewing setuptools/command/egg_info.py and setuptools/_distutils/filelist.py, the two affected FileList implementations named in the report. Check how MANIFEST.in exclusions are matched against walked paths, then verify the work addresses normalization-insensitive matching and the affected package is on fixed version 83.0.0.

Written by the indexing model from the issue text.