technology.jgit: Improper handling of case insensitive filesystems in JGit allows arbitrary file write

The Eclipse Foundation is a Common Vulnerabilities and Exposures (CVE) Numbering Authority. This issue it used to request and track the progress of the assignment of a CVE for a vulnerability in the project code for an Eclipse open source project.

Basic information

Project name: Eclipse JGit

Project id: technology.jgit

Request type: publication

Versions affected: all versions <= 6.6.0.202305301015-r

Common Weakness Enumeration:

• CWE-59: Improper Link Resolution Before File Access ('Link Following')
• CWE-178: Improper Handling of Case Sensitivity

Common Vulnerability Scoring System: 3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

Common Attack Pattern Enumeration and Classification: CAPEC-132: Symlink Attack

Summary:

Arbitrary File Overwrite in Eclipse JGit <= 6.6.0

In Eclipse JGit, all versions <= 6.6.0.202305301015-r, a symbolic link present in a specially crafted git repository can be used to write a file to locations outside the working tree when this repository is cloned with JGit to a case-insensitive filesystem, or when a checkout from a clone of such a repository is performed on a case-insensitive filesystem.

This can happen on checkout (DirCacheCheckout), merge (ResolveMerger via its WorkingTreeUpdater), pull (PullCommand using merge), and when applying a patch (PatchApplier). This can be exploited for remote code execution (RCE), for instance if the file written outside the working tree is a git filter that gets executed on a subsequent git command.

The issue occurs only on case-insensitive filesystems, like the default filesystems on Windows and macOS. The user performing the clone or checkout must have the rights to create symbolic links for the problem to occur, and symbolic links must be enabled in the git configuration.

Setting git configuration option core.symlinks = false before checking out avoids the problem.

The issue was fixed in Eclipse JGit version 6.6.1.202309021850-r and 6.7.0.202309050840-r, available via Maven Central and repo.eclipse.org.

Credits: the JGit maintainers would like to thank RyotaK for finding and reporting this issue.

Links:

• Bug tracker

Tracking

This section will completed by the project team.

• Reserve an entry only
• We're ready for this issue to be reported to the central authority (i.e., make this public now)
• (when applicable) The GitHub Security Advisory is ready to be published now

Mikaël already reserved CVE-2023-4759 for this vulnerability.

Note that for those projects that host their repositories on GitHub, the use of GitHub Security Advisories is recommended but is not required.

This section will be completed by the EMO.

CVE: {cve}

• All required information is provided
• CVE Assigned
• Pushed to Mitre
• Accepted by Mitre