GHSA-r9mr-m37c-5fr3
ADVISORY - githubSummary
Summary
GitPython's check_unsafe_options guard (the control introduced by CVE-2026-42215 / GHSA-2f96 and hardened since) can be bypassed for every guarded method (clone/clone_from, fetch/pull/push, ls_remote, iter_commits, blame, archive) by smuggling an option token inside the VALUE of a single-character kwarg. In the default allow_unsafe_options=False configuration this yields arbitrary command execution via --upload-pack.
Root Cause
The guard builds its candidate option list from kwarg KEYS only: _option_candidates([], {"n":"--upload-pack=<cmd>"}) returns ['-n'] (cmd.py:1042-1046 derives the candidate from the key, never the value). -n is not on the denylist, so check_unsafe_options passes. But transform_kwarg('n', value, split_single_char_options=True) (cmd.py:1600-1606) emits two argv tokens ['-n', '--upload-pack=<cmd>']. git then parses the second token as --upload-pack and executes the attacker-supplied command. The guard never inspects the value that becomes a separate argv token.
Impact
Arbitrary OS command execution as the host process (via --upload-pack) in the default configuration, affecting all guarded methods since they all build candidates through the name-only _option_candidates.
Proof of Concept
from git import Repo
Repo.clone_from(bare_repo, out_dir, n="--upload-pack=touch /tmp/ACE;git-upload-pack")
# /tmp/ACE created -> ACE. Direct-name form upload_pack="..." is correctly BLOCKED.
File-write variant on a guarded revision command: iter_commits('HEAD', g='--output=/path') -> candidate ['-g'] passes, argv ['-g','--output=/path'], victim file truncated.
Attack Chain
- Entry: app forwards a user-supplied options dict ->
Repo.clone_from(url, path, n="--upload-pack=touch /tmp/ACE;git-upload-pack"). Guard:check_unsafe_options(options=_option_candidates([], kwargs), unsafe=unsafe_git_clone_options)at base.py. Bypass proof:_option_candidates([], {"n":"--upload-pack=..."})->['-n'](key-only), not on denylist -> no UnsafeOptionError (verified live). - Transform:
transform_kwarg('n', value, split_single_char_options=True)->['-n', '--upload-pack=touch /tmp/ACE;git-upload-pack']. Guard: none (guard already passed on name-only candidate). Bypass proof: verified transform emits two tokens. - Sink:
git clone -n --upload-pack='touch ...;git-upload-pack' -- <src> <dst>; git parses and runs the second token. Impact: ACE (marker created, verified end-to-end).
Bypass Evidence
Live-verified on HEAD (tag 3.1.53): _option_candidates returns key-only candidate ['-n']; transform_kwargs emits the smuggled --upload-pack= token; clone_from with the payload created the marker file; the direct-name upload_pack= form raised UnsafeOptionError. All prior bypasses (GHSA-rpm5 underscore key, GHSA-2f96 long-option abbreviation, GHSA-v396 joined short option, GHSA-x2qx multi-before-split) are BLOCKED on HEAD — this is a distinct kwarg-value->separate-token vector.
Affected Versions
<= 3.1.53
Suggested Fix
Make _option_candidates also emit candidates derived from single-character kwarg VALUES when split_single_char_options is in effect, OR run check_unsafe_options over the fully-transformed argv rather than the reconstructed name-only candidate list.
Reported by zx (Jace) — GitHub: @manus-use
GitHub
CVSS SCORE
8.8high| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| gitpython | pypi | - | - | <=3.1.53 | 3.1.54 |
CVSS:3 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The attacker requires privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
The vulnerable system can be exploited without interaction from any user.
An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any or all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component.