Summary
GitPython 3.1.59 blocks a previously available local-file read path through unsafe git diff options such as -O/--orderfile.
However, the high-level diff API still permits --no-index with the default allow_unsafe_options=False.
--no-index changes the semantics of the paths arguments: instead of repository-relative pathspecs, Git interprets them as arbitrary filesystem paths.
When combined with the still-allowed -I/--ignore-matching-lines option, this creates a content-dependent Boolean oracle over a caller-selected local file.
This was reproduced against the published GitPython 3.1.59 wheel.
The original unsafe-option path is blocked in 3.1.59, while this alternate path remains reachable without setting allow_unsafe_options=True.
Details
Confirmed API surface:
repo.index.diff(
None,
no_index=True,
I=pattern,
paths=[baseline_path, target_path],
create_patch=True,
)
The relevant behavior is:
- --no-index makes the two values supplied via paths filesystem operands rather than repository pathspecs.
- -I/--ignore-matching-lines makes Git's result depend on whether the supplied regular expression matches the relevant file content.
- GitPython exposes the resulting bit through distinguishable behavior:
- matching condition: normal return with an empty DiffIndex
- non-matching condition: GitCommandError with exit status 1
An application that forwards attacker-influenced diff options and paths and exposes the success/error distinction can therefore be queried repeatedly to recover a guessable local single-line secret.
The issue was confirmed with the default allow_unsafe_options=False.
The behavior does not require the caller to explicitly opt into GitPython's unsafe-option mode.
Verified intended security boundary:
- GitPython 3.1.58 accepts the earlier -O/--orderfile local-file input path.
- GitPython 3.1.59 rejects that same path with UnsafeOptionError.
- GitPython 3.1.59 still permits the --no-index alternate path described above.
This appears to be an alternate route to the same local-file confidentiality property that the 3.1.59 diff option hardening is intended to protect.
PoC
A minimal reproducer, controlled extraction demonstrator, proof matrix, and proposed remediation are included in the attached package.
gitpython-3159-maintainer-evidence.zip
The minimal reproducer creates only temporary researcher-controlled files and demonstrates the following predicate:
correct prefix -> normal GitPython return
incorrect prefix -> GitCommandError(status=1)
In the controlled extraction test, I generated three independent random single-line values and recovered all three exactly through repeated calls to the GitPython high-level API.
Result: 3/3 recovered.
The extraction harness also installs a Python audit hook that rejects direct Python open() access to the target file during the oracle phase. The content-dependent read is therefore performed by the child git process invoked through GitPython rather than by the reproduction script directly.
Controls were also tested:
- normal repository-scoped diff: no secret disclosure
- same outside paths without --no-index: no arbitrary-filesystem interpretation
- deliberately incorrect predicate: status 1 as expected
Suggested remediation is to classify --no-index as unsafe for the high-level diff API unless the caller explicitly sets allow_unsafe_options=True.
Impact
Potential impact is disclosure of local files readable by the process running GitPython.
Exploitation requires an embedding application to allow an attacker to influence:
- the relevant diff options,
- both path operands, and
- repeated requests while exposing a distinguishable success/error result.
The demonstrated attack is a blind content oracle rather than a one-request in-band file read. It is particularly applicable to short or structured single-line secrets where the target path and approximate value format are known or guessable.
Confirmed affected release: GitPython 3.1.59.
References
kokomaru167 Reporter
Summary
GitPython 3.1.59 blocks a previously available local-file read path through unsafe git diff options such as -O/--orderfile.
However, the high-level diff API still permits --no-index with the default allow_unsafe_options=False.
--no-index changes the semantics of the paths arguments: instead of repository-relative pathspecs, Git interprets them as arbitrary filesystem paths.
When combined with the still-allowed -I/--ignore-matching-lines option, this creates a content-dependent Boolean oracle over a caller-selected local file.
This was reproduced against the published GitPython 3.1.59 wheel.
The original unsafe-option path is blocked in 3.1.59, while this alternate path remains reachable without setting allow_unsafe_options=True.
Details
Confirmed API surface:
repo.index.diff(
None,
no_index=True,
I=pattern,
paths=[baseline_path, target_path],
create_patch=True,
)
The relevant behavior is:
An application that forwards attacker-influenced diff options and paths and exposes the success/error distinction can therefore be queried repeatedly to recover a guessable local single-line secret.
The issue was confirmed with the default allow_unsafe_options=False.
The behavior does not require the caller to explicitly opt into GitPython's unsafe-option mode.
Verified intended security boundary:
This appears to be an alternate route to the same local-file confidentiality property that the 3.1.59 diff option hardening is intended to protect.
PoC
A minimal reproducer, controlled extraction demonstrator, proof matrix, and proposed remediation are included in the attached package.
gitpython-3159-maintainer-evidence.zip
The minimal reproducer creates only temporary researcher-controlled files and demonstrates the following predicate:
correct prefix -> normal GitPython return
incorrect prefix -> GitCommandError(status=1)
In the controlled extraction test, I generated three independent random single-line values and recovered all three exactly through repeated calls to the GitPython high-level API.
Result: 3/3 recovered.
The extraction harness also installs a Python audit hook that rejects direct Python open() access to the target file during the oracle phase. The content-dependent read is therefore performed by the child git process invoked through GitPython rather than by the reproduction script directly.
Controls were also tested:
Suggested remediation is to classify --no-index as unsafe for the high-level diff API unless the caller explicitly sets allow_unsafe_options=True.
Impact
Potential impact is disclosure of local files readable by the process running GitPython.
Exploitation requires an embedding application to allow an attacker to influence:
The demonstrated attack is a blind content oracle rather than a one-request in-band file read. It is particularly applicable to short or structured single-line secrets where the target path and approximate value format are known or guessable.
Confirmed affected release: GitPython 3.1.59.
References