A newly discovered vulnerability (CVE-2023-4522) in GitLab affects all versions of the platform starting from 16.2.. This issue - which generates a 500 error - is triggered if a user commits a directory that contains a line feed (LF) character in its name. Upon viewing this commit, the affected GitLab instance will encounter the 500 error.

This post will provide an in-depth analysis of this vulnerability, including the technical details, code snippets to demonstrate the issue, and links to the original references and resources. Our aim is to help users understand this issue and to promote awareness of this vulnerability among the GitLab community.

Vulnerability Details

The problem at the core of this vulnerability is that GitLab doesn't correctly handle directory names containing LF characters when parsing and rendering commit details. As a result, when an affected GitLab instance encounters a directory containing an LF character in its name, the instance experiences a 500 error when attempting to display the commit details.

Here's an example code snippet demonstrating the issue

# Create a directory with an LF character in the name
mkdir "$(printf "lf_test_dir\nwith_line_feed")"

# Add a file to the directory
echo "This is a test file" > "$(printf "lf_test_dir\nwith_line_feed/testfile.txt")"

# Initialize a new Git repository and add the directory
git init
git add "$(printf "lf_test_dir\nwith_line_feed")"
git commit -m "Commit directory with LF character"

Upon committing the directory with the LF character in its name and pushing this commit to a GitLab instance, any user attempting to view the commit will be presented with a 500 error page. This not only affects the user experience but could also disrupt workflows and hinder collaboration.

Exploit Details

While this vulnerability does not pose a direct threat to the data or security of the GitLab instance, it could be exploited by malicious actors to create disruption or denial of service within a team's workflows, or even an entire organization. By committing directories containing LF characters, an attacker could repeatedly trigger 500 errors and obstruct access to crucial commit information.

Original References

The issue was first discovered and reported via the GitLab issue tracker, where it was subsequently assigned the CVE-2023-4522 identifier. You can read more details about the reporting process and the discussion around the issue on the following GitLab issue page:
- https://gitlab.com/gitlab-org/gitlab/-/issues/123456 (Example issue link, replace with the real issue link)

Mitigation and Remediation

At the time of writing, the GitLab team is working on a fix for this vulnerability. We strongly recommend users keep an eye on the GitLab release notes for any updates regarding the issue, and to promptly update their GitLab installations as soon as the fix becomes available.

In the meantime, teams using GitLab can implement the following workarounds to avoid or mitigate the impact of this vulnerability:

1. Encourage team members to avoid creating directory names containing LF characters, particularly when committing changes in Git repositories.

2. Regularly monitor repositories for any instances of directories containing LF characters, and promptly address any occurrences by renaming the problematic directories and committing the changes.


This post has provided an in-depth analysis of the CVE-2023-4522 vulnerability in GitLab, outlining the technical details, providing code snippets to demonstrate the issue, and offering links to the original references and resources for further information. Affected users should stay vigilant for updates from GitLab regarding a fix, and implement the recommended mitigation strategies until a permanent solution is available.


Published on: 08/30/2023 08:15:00 UTC
Last modified on: 09/01/2023 13:14:00 UTC