CVE-2026-53584 in libgit2
Summary
by MITRE • 08/20/2026
libgit2 is a portable C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Prior to 1.8.6 and 1.9.5, libgit2 does not reject traversal components in a submodule path loaded from .gitmodules. The affected src/libgit2/submodule.c paths include git_submodule_lookup and git_submodule_add_setup. A crafted repository can specify a path such as ../escape-target, and applications that initialize the submodule can create directories outside the repository working tree. This issue is fixed in versions 1.8.6 and 1.9.5.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified in libgit2 prior to versions 1.8.6 and 1.9.5 represents a critical path traversal flaw within the submodule handling mechanisms of this widely used C library for Git operations. Libgit2 serves as a portable implementation of core Git methods, enabling developers to integrate version control functionality directly into their applications through a robust API. However, during the processing of repository configurations, specifically when loading and validating paths defined in .gitmodules files, the library failed to adequately sanitize or reject traversal components such as double dots followed by forward slashes. This deficiency allows an attacker who controls the contents of a remote repository to manipulate the intended directory structure where submodules are checked out.
The technical root cause lies within specific functions responsible for submodule management, namely git_submodule_lookup and git_submodule_add_setup located in src/libgit2/submodule.c. When these functions process path specifications from .gitmodules entries, they do not perform sufficient validation to ensure that the resulting file paths remain strictly confined within the repository's working tree boundaries. Consequently, if a crafted repository specifies a submodule path containing directory traversal sequences like ../escape-target, libgit2 will interpret this literally and proceed with creating directories at those relative locations. This behavior bypasses the expected security boundary of the local repository workspace.
The operational impact of this vulnerability is significant for any application that utilizes libgit2 to initialize or update submodules from untrusted sources. An attacker can exploit this flaw by publishing a malicious repository configured with submodule paths pointing outside the target directory structure. When a victim application initializes these submodules, it inadvertently creates files and directories in arbitrary locations on the file system relative to where the library is executing. This capability effectively allows for arbitrary file creation or overwriting depending on the permissions of the user running the application. Such behavior can lead to code injection if executable scripts are placed in expected execution paths, configuration poisoning by modifying critical config files located outside the repo, or general disruption of system integrity through unauthorized directory structures being established on the host machine.
This vulnerability aligns with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, as it involves failing to restrict file operations to an intended location. From a threat modeling perspective using MITRE ATT&CK, this behavior facilitates Initial Access and potentially Persistence or Privilege Escalation depending on the context in which libgit2 is deployed and executed by end users. The ability to write files outside of designated directories undermines the isolation guarantees expected from version control operations.
Mitigation for this issue requires upgrading libgit2 to versions 1.8.6 or later, where the path validation logic has been corrected to reject traversal components in submodule paths. Applications relying on older versions should implement additional defensive checks before invoking submodule initialization functions, ensuring that resolved absolute paths remain within the expected repository root directory. Developers must also exercise caution when processing .gitmodules files from untrusted repositories and consider validating all incoming file system operations against a whitelist of allowed directories to prevent similar path traversal exploits in other parts of their codebase.