CVE-2026-87817 in GitPython
Summary
by MITRE • 09/09/2026
GitPython before 3.1.60 fails to properly validate the git directory location, allowing attackers to impersonate the git directory using tracked files like gitdir, commondir, and HEAD. Attackers can execute arbitrary code by placing a malicious pre-commit hook in the tracked hooks directory that executes when a victim calls index.commit() on a cloned or opened repository.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified in GitPython versions prior to 3.1.60 represents a critical flaw in how the library handles path validation and file system interactions during git operations, specifically within the context of cloning or opening repositories. This issue stems from an insufficient validation mechanism that fails to properly verify the integrity and location of the underlying git directory structure. In standard git workflows, certain files such as .gitmodules, config files containing gitdir directives, and HEAD references are used to manage submodules and repository links. However, in this vulnerable implementation, these tracked files can be manipulated by an attacker who has write access to a remote repository or its contents. By crafting malicious versions of these configuration files, specifically targeting the gitdir, commondir, and HEAD entries, an adversary can redirect GitPython's internal path resolution logic away from the intended safe directory structure toward a location controlled by the attacker. This misdirection is not merely cosmetic; it fundamentally alters where subsequent file system operations are executed, creating a pathway for arbitrary code execution that bypasses standard security boundaries expected in version control systems.
The operational impact of this vulnerability is severe because it directly compromises the integrity and confidentiality of the victim's environment through remote code execution. When a developer or automated process invokes index.commit() on a repository cloned from or opened at a malicious source, GitPython processes the manipulated configuration files without adequate sanitization. This allows an attacker to place a malicious pre-commit hook within the tracked hooks directory associated with the compromised git structure. Pre-commit hooks are scripts that run automatically before each commit is finalized, providing a legitimate execution context for arbitrary commands under the privileges of the user running the GitPython process. Consequently, when the victim attempts to commit changes, the system executes the attacker's payload without any explicit interaction or warning from the application layer. This effectively turns routine version control operations into vectors for malware deployment, data exfiltration, or further lateral movement within a networked environment where such repositories are commonly used as part of continuous integration and development pipelines.
From a classification perspective, this vulnerability aligns with CWE-20 Improper Input Validation, as the core failure lies in the application's inability to correctly validate user-supplied input derived from repository metadata files. Furthermore, it relates closely to CWE-94 Code Injection, specifically through the exploitation of hook scripts which are essentially executable code stored within the version control system itself. In terms of adversary tactics and techniques, this scenario maps directly to ATT&CK technique T1059 Command and Scripting Interpreter, where attackers use native operating system utilities or scripting languages like Python Bash or PowerShell to execute commands. Additionally, it reflects aspects of T1496 Resource Hijacking if the executed code consumes resources for cryptomining, or more critically T1203 Exploitation for Client Execution if this is part of a broader phishing campaign targeting developers who clone untrusted repositories. The vulnerability exploits the trust relationship between the developer and the repository source, leveraging the automated nature of git operations to achieve persistence and execution without direct user intervention beyond initiating the commit action.
Mitigation strategies must focus on immediate version updates and enhanced input sanitization practices within development workflows. Organizations relying on GitPython should upgrade immediately to version 3.1.60 or later, where this path validation logic has been corrected to ensure that git directory locations are strictly validated against expected safe paths before any operations are performed. For environments unable to patch instantly, defensive coding patterns can be employed, such as implementing strict allow-lists for allowed directories and disabling hook execution entirely if the repository source is not fully trusted or verified via cryptographic signatures like GPG commits. Security teams should also audit their CI/CD pipelines to ensure that repositories cloned from external sources are scanned for malicious hooks before any automated build or commit processes are triggered. Additionally, implementing runtime application self-protection (RASP) solutions can help detect anomalous process executions originating from git-related scripts, providing an additional layer of defense against exploitation attempts targeting this specific class of vulnerabilities in version control libraries.