CVE-2026-54528 in Git Plugin
Summary
by MITRE • 07/09/2026
JupyterLab Git is a Git extension for JupyterLab. Prior to 0.54.0, jupyterlab-git uses fnmatch.fnmatchcase() in GitHandler.prepare() in jupyterlab_git/handlers.py to enforce excluded_paths, allowing an authenticated user on a case-insensitive filesystem to vary URL path casing and read excluded directories. This issue is fixed in version 0.54.0.
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Analysis
by VulDB Data Team • 07/09/2026
The vulnerability in JupyterLab Git extension affects versions prior to 0540 where the git extension fails to properly validate file paths when enforcing excluded directories. The flaw resides in the GitHandler.prepare() method within jupyterlab_git/handlers.py which utilizes fnmatch.fnmatchcase() function for path validation. This function performs case-sensitive pattern matching but when combined with how directory exclusions are processed, it creates a security gap that allows authenticated users to bypass access controls on case-insensitive filesystems.
The technical implementation of this vulnerability stems from the improper handling of path case variations in the exclusion mechanism. When fnmatch.fnmatchcase() is used for validating excluded paths, it does not account for case variations that might occur in file system paths on case-insensitive systems such as those running on windows or macos. An attacker can exploit this by crafting URLs with different casing patterns that match the excluded directory patterns but are not actually excluded due to the case-sensitive nature of the matching function.
This vulnerability enables a privilege escalation scenario where authenticated users can access directories and files that should be excluded from git operations. The impact extends to potential information disclosure, as attackers could read sensitive data stored in directories that are meant to be protected by exclusion rules. The security implications are particularly severe in collaborative environments where multiple users have access to the same JupyterLab instance and where directory-level access controls are essential for maintaining data integrity.
The issue represents a failure in input validation and access control enforcement, specifically related to path handling and pattern matching implementations. According to CWE classification, this vulnerability aligns with CWE-20: Improper Input Validation and potentially CWE-264: Permissions, Privileges, and Access Controls. The attack vector can be categorized under credential exposure and information disclosure techniques in the MITRE ATT&CK framework, specifically related to privilege escalation through access control bypass.
The fix implemented in version 0540 addresses this by modifying how excluded paths are handled, ensuring that case variations are properly accounted for during validation. This update likely involves changing the path matching logic to be more robust against case variations or implementing additional checks to ensure that all possible case permutations of excluded directories are properly recognized and enforced. Organizations using JupyterLab Git should immediately upgrade to version 0540 or later to remediate this vulnerability and prevent potential unauthorized access to restricted directories in their git operations.
The vulnerability highlights the importance of consistent path handling across different filesystem types and the need for comprehensive testing on case-insensitive systems. It demonstrates that even seemingly simple path validation functions can create security gaps when not properly considering all possible input variations and system characteristics. This issue serves as a reminder of the critical nature of access control implementations in web-based development environments where multiple users interact with shared resources and sensitive data repositories through git operations.