GHSA-jm78-9fvv-mhgr CVE-2026-76221 PYSEC-2026-3783

GitPython: git-config OPTION-name injection via =/#/whitespace bypasses name validator, enabling forged core.sshCommand/hooksPath (RCE)

High PyPI

Severity: 0.0 / 10; High · CVSS 4.0
Exploit chance (EPSS): 0.48%; Chance of exploitation in the next 30 days. Higher than 41.77% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection'); CWE-88 Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
Fix: 3.1.58; Upgrade gitpython to this version or later

Description

Summary

GitPython's config-name validator only neutralizes CR/LF/NUL for the "option" label; it does not reject =, #, ;, [, ], or whitespace in an option name. write_section writes the option name verbatim into the config file, so an option name such as sshCommand = touch <cmd> # is written as \tsshCommand = touch <cmd> # = <value>, which git parses as core.sshCommand = touch <cmd> (the trailing # comments out the intended value). This forges arbitrary config directives (core.sshCommand, core.hooksPath, alias.*) → RCE on the next git operation. This is a distinct field (option name, not section name) and distinct character class (=/#/space, not newline/bracket) from GHSA-3rp5-jjmw-4wv2 (section-name bracket injection) and GHSA-mv93-w799-cj2w / GHSA-v87r-6q3f-2j67 (newline injection).

Root Cause

_assure_config_name_safe(name, label) (git/config.py:897) applies the bracket/quote state machine ONLY when label == "section"; for the "option" label it falls through with just the UNSAFE_CONFIG_CHARS_RE = [\r\n\x00] regex. write_section then writes the option name verbatim into "\t%s = %s\n" (config.py:702).

Impact

Arbitrary git-config directive injection → remote code execution via core.sshCommand (fires on any ssh git operation, no staged file needed) or core.hooksPath (with a staged hook). Requires the embedding application to forward a caller-influenced OPTION NAME into the config writer (name-control model, the same name-control model accepted by the related published advisories GHSA-3rp5-jjmw-4wv2 and GHSA-mv93-w799-cj2w). Default configuration.

Proof of Concept

with repo.config_writer() as cw:
    cw.set_value("core", "sshCommand = touch /tmp/RCE #", "x")
# git config --get core.sshCommand  ->  touch /tmp/RCE

Attack Chain

Entry: app calls config writer with attacker-controlled OPTION name: set_value("core", "sshCommand = touch /tmp/RCE #", "x").
Check: _assure_config_name_safe(option, "option") @ config.py. Guard: regex matches only [\r\n\x00]; bracket/quote state machine is gated on label=="section". Bypass proof: =,#,space pass → no ValueError.
Sink: write_section writes "\tsshCommand = touch /tmp/RCE # = x\n" (config.py:702).
Impact: git parses core.sshCommand=touch /tmp/RCE → arbitrary code execution on next git op.

Bypass Evidence

Independently reproduced (gate harness): set_value('core','sshCommand = touch <RCE> #','x') → no ValueError; file line sshCommand = touch <RCE> # = x; git config --get core.sshCommand → touch <RCE> (rc=0). Also verified core.hooksPath via both GitConfigParser and repo.config_writer(). Fix-commit read: bracket/quote checks are inside if label == "section"; the "option" label is not covered.

Affected Versions

GitPython <= 3.1.57 (validator present verbatim on the latest release tag).

Suggested Fix

Apply the section-name safety checks (reject =, #, ;, [, ], whitespace) to the "option" label as well, or validate the fully-rendered config line after substitution.

Reported by zx (Jace) — GitHub: @manus-use

Affected versions

PyPI

Package	Vulnerable	Fixed in
gitpython	`< 3.1.58`	`3.1.58`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

gitpython PyPI → `3.1.58`

pip

pip install --upgrade "gitpython>=3.1.58"

poetry

poetry add "gitpython>=3.1.58"

uv

uv add "gitpython>=3.1.58"

Severity breakdown

CVSS 4.0 0.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack vector: Network
Attack complexity: Low
Attack requirements: None
Privileges required: Low
User interaction: None
Confidentiality (vulnerable system): High
Integrity (vulnerable system): High
Availability (vulnerable system): High
Confidentiality (subsequent systems): None
Integrity (subsequent systems): None
Availability (subsequent systems): None
Exploit maturity: Not defined
Scope: X

CVSS 3.1 8.8

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

Weakness

CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.

How to prevent it

Requirements: Programming languages and supporting technologies might be chosen which are not subject to these issues.
Implementation: Utilize an appropriate mix of allowlist and denylist parsing to filter control-plane syntax from all input.

CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.