title: Improper handling of case insensitive filesystems in Eclipse JGit allows arbitrary file write
description: 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 https://repo1.maven.org/maven2/org/eclipse/jgit/  and  repo.eclipse.org https://repo.eclipse.org/content/repositories/jgit-releases/ . A backport is available in 5.13.3 starting from  5.13.3.202401111512-r.
The JGit maintainers would like to thank RyotaK for finding and reporting this issue.
problem types: CWE-59 Improper Link Resolution Before File Access ('Link Following')
affected:
{
collectionURL: https://git.eclipse.org/c/jgit/jgit.git/
defaultStatus: unaffected
product: Eclipse JGit
vendor: Eclipse Foundation
versions:
lessThanOrEqual: 6.6.0.202305301015-r, status: affected, version: 0.0.0, versionType: semver
status: unaffected, version:   5.13.3.202401111512-r
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 8.8
baseSeverity: HIGH
confidentialityImpact: HIGH
integrityImpact: HIGH
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: REQUIRED
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
version: 3.1
]
format: CVSS
scenarios: GENERAL
workarounds: Setting git configuration option core.symlinks = false before checking out avoids the problem.