[renovate-bot]

This PR contains the following updates:

Package	Change	Age	Confidence
setuptools (changelog)	<82 → <85

---

setuptools: MANIFEST.in exclusion bypass in sdist via Unicode normalization collision (NFC/NFD) on macOS APFS/HFS+

CVE-2026-59890 / GHSA-h35f-9h28-mq5c

More information

Details

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.

Details

File names in FileList.files come from os.walk (setuptools/_distutils/filelist.py, _find_all_simple), so on APFS a file written NFD is offered to the matcher in NFD, while the MANIFEST.in pattern carries the author's editor form (typically NFC). The matching path performs no canonicalization:

##### setuptools/command/egg_info.py  (FileList.global_exclude)
def global_exclude(self, pattern):
    match = translate_pattern(os.path.join('**', pattern))   # fnmatch.translate -> regex, no NFC/NFD
    return self._remove_files(match.match)                   # byte-level regex over raw os.walk names

A rule written NFC (café = 63 61 66 c3 a9) does not match an on-disk name written NFD (café = 63 61 66 65 cc 81), even though the filesystem treats the two as one file.

A unicodedata.normalize('NFD', ...) helper exists in setuptools/unicode_utils.py (decompose()), but it is never called in the manifest matching path, so neither the pattern nor the walked path is normalized before matching. The only normalization in this area, EggInfoCommand._manifest_normalize, uses filesys_decode (bytes→str decode only, no NFC/NFD) and runs when writing SOURCES.txt, after matching has already occurred.

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.

Proof of concept

With a project containing MANIFEST.in:

global-include *.txt *.json
global-exclude secret_café.txt    # rule saved NFC

and an on-disk file secret_café.txt written in NFD, python -m build --sdist packs the secret file into the resulting .tar.gz, while an ASCII control file excluded by the same directive is correctly dropped — isolating the bypass to the NFC-pattern vs. NFD-name mismatch. Reproduced on macOS APFS with setuptools 82.0.1.

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.

Severity

• CVSS Score: 6.1 / 10 (Medium)
• Vector String: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

References

• https://github.com/pypa/setuptools/security/advisories/GHSA-h35f-9h28-mq5c
• https://nvd.nist.gov/vuln/detail/CVE-2026-59890
• https://github.com/pypa/setuptools/commit/dd9f436a36486b4cb8a4c70a2321548b0be09b8f
• https://github.com/pypa/advisory-database/tree/main/vulns/setuptools/PYSEC-2026-3447.yaml
• https://github.com/pypa/setuptools/releases/tag/v83.0.0
• https://github.com/advisories/GHSA-h35f-9h28-mq5c

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Release Notes

pypa/setuptools (setuptools)

v84.2.0

Compare Source

v84.1.0

Compare Source

v84.0.0

Compare Source

v83.0.0

Compare Source

v82.0.1

Compare Source

v82.0.0

Compare Source

---

Configuration

📅 Schedule: (UTC)

• Branch creation
  • At any time (no schedule defined)
• Automerge
  • At any time (no schedule defined)

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.