CVE-2018-17452 in Community Edition
Summary
by MITRE • 04/16/2023
An issue was discovered in GitLab Community and Enterprise Edition before 11.1.7, 11.2.x before 11.2.4, and 11.3.x before 11.3.1. There is Server-Side Request Forgery (SSRF) via a loopback address to the validate_localhost function in url_blocker.rb.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/05/2023
This vulnerability resides in GitLab's URL validation mechanism within the url_blocker.rb file, where a server-side request forgery flaw allows attackers to bypass localhost restrictions through a loopback address. The issue affects multiple versions of GitLab Community and Enterprise Edition, specifically those before 11.1.7, 11.2.4, and 11.3.1, creating a significant security risk for organizations relying on these platforms. The vulnerability stems from improper handling of localhost validation, allowing malicious actors to make unauthorized requests to internal services that should be restricted.
The technical flaw manifests in the validate_localhost function which fails to properly sanitize or restrict loopback address access. When GitLab processes URLs containing localhost references, the validation logic does not adequately prevent requests to internal network resources that should remain isolated from external access. This creates an attack surface where remote adversaries can potentially access internal services, databases, or other sensitive components that are typically protected by network segmentation. The vulnerability is categorized under CWE-918 as Server-Side Request Forgery, which specifically addresses the issue of untrusted inputs being used to make requests to internal systems.
The operational impact of this vulnerability is substantial, as it enables attackers to potentially access internal GitLab services, databases, or other networked systems that are normally protected by firewall rules or network isolation. An attacker could leverage this to perform reconnaissance, access sensitive data, or potentially escalate privileges within the internal network. This type of vulnerability aligns with ATT&CK technique T1071.004 for Application Layer Protocol: DNS, where attackers exploit validation flaws to bypass network restrictions. The vulnerability essentially allows an attacker to use the GitLab instance as a proxy to access internal resources that should remain protected.
Organizations should immediately upgrade to GitLab versions 11.1.7, 11.2.4, or 11.3.1 to remediate this vulnerability. Additional mitigations include implementing network-level restrictions to prevent outbound requests to internal services, configuring proper firewall rules, and monitoring for suspicious URL patterns in GitLab logs. Security teams should also review their GitLab configurations to ensure that localhost validation is properly enforced and that internal services are adequately isolated from the GitLab instance's network access. The vulnerability highlights the importance of proper input validation and the need for robust network segmentation policies to prevent lateral movement within internal networks.