Dulwich: Symlink write-through in checkout(paths=[]) via raw os.open bypasses all symlink protections — GHSA-8W8G-WQ8H-FQ33

Summary

## Summary Dulwich's `porcelain.checkout(paths=[...])` code path writes files using raw `os.open(file_path, O_WRONLY|O_CREAT|O_TRUNC, mode)` followed by `f.write(obj.data)`. This code path does NOT call `build_file_from_blob()` at all, completely bypassing any symlink protections (including the unreleased d09f8af fix). `os.open` without `O_NOFOLLOW` follows symlinks at both the target file and intermediate…

Timeline

Published by source

2026-10-02

Risk context

• Reported severity or threat level: high.
• Reported CVSS score: 8.6 out of 10.
• Review exposure for the affected product or family: pip: dulwich.

Product

pip: dulwich

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source

Evidence and provenance

Canonical advisory ID

GHSA-8W8G-WQ8H-FQ33

Source

GitHub

Vendor

GitHub

Published by source

2026-10-02

Last source activity

2026-10-02

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.