Eclipse JGit <=6.6.0 Symbolic Link Arbitrary File Overwrite
CVE-2023-4759 Published on September 12, 2023
Improper handling of case insensitive filesystems in Eclipse JGit allows arbitrary file write
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.
Vulnerability Analysis
CVE-2023-4759 can be exploited with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Types
What is an insecure temporary file Vulnerability?
The software attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
CVE-2023-4759 has been classified to as an insecure temporary file vulnerability or weakness.
Improper Handling of Case Sensitivity
The software does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.
Products Associated with CVE-2023-4759
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Affected Versions
Eclipse Foundation Eclipse JGit:- Version 0.0.0, <= 6.6.0.202305301015-r is affected.
- Version 5.13.3.202401111512-r is unaffected.
- Before and including 6.6.0.202305301015-r is affected.
- Version 5.13.3.202401111512-r is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.