CVE-2018-20497 in Community Edition
Summary
by MITRE
An issue was discovered in GitLab Community and Enterprise Edition before 11.4.13, 11.5.x before 11.5.6, and 11.6.x before 11.6.1. It allows SSRF.
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Analysis
by VulDB Data Team • 03/18/2024
The vulnerability identified as CVE-2018-20497 represents a significant server-side request forgery flaw affecting GitLab Community and Enterprise Edition installations across multiple version branches. This issue exists within the web application's handling of external resource requests and allows malicious actors to manipulate the system into making unintended requests to internal or external systems. The vulnerability specifically impacts versions prior to 11.4.13, 11.5.6, and 11.6.1, indicating a widespread exposure across the GitLab product line during this period. The SSRF vulnerability stems from insufficient input validation and sanitization of URLs and resource identifiers within GitLab's web interface, creating a pathway for attackers to bypass normal access controls and potentially gain unauthorized access to internal network resources.
The technical exploitation of this vulnerability occurs when GitLab processes user-supplied URLs or resource identifiers without proper validation mechanisms. Attackers can craft malicious requests that trick the GitLab application into initiating connections to internal services, external malicious servers, or performing unauthorized operations against configured external integrations. This flaw enables attackers to perform reconnaissance activities by scanning internal network ranges, access internal services that should normally be restricted, or even exfiltrate sensitive data from internal systems. The vulnerability is particularly dangerous because GitLab installations often have access to various internal systems and services through their integration capabilities, making the potential attack surface quite extensive. The flaw manifests when the application fails to properly validate or sanitize user input before using it in HTTP requests or API calls, allowing arbitrary URLs to be processed through the system's network communication mechanisms.
The operational impact of CVE-2018-20497 extends beyond simple data theft or service disruption, as it can enable attackers to perform lateral movement within network environments where GitLab instances are deployed. Organizations using affected GitLab versions face potential exposure to internal network scanning, access to sensitive internal services, and possible data exfiltration through the compromised system. The vulnerability can be exploited to target internal databases, authentication systems, or other critical infrastructure that may be accessible through the network paths that GitLab uses for its various integration features. This presents a significant risk for organizations that rely on GitLab for code repository management and CI/CD processes, as the compromised system could provide attackers with access to source code repositories, build artifacts, and potentially sensitive configuration data. The impact is further amplified by the fact that GitLab installations often serve as central points of access for development teams and may have elevated privileges within organizational networks.
Mitigation strategies for CVE-2018-20497 require immediate patching of affected GitLab installations to versions 11.4.13, 11.5.6, or 11.6.1, respectively, depending on the current version in use. Organizations should also implement network-level restrictions and firewall rules to prevent outbound connections from GitLab instances to internal systems, particularly those that should not be accessible through the application. Input validation should be strengthened at multiple layers, including web application firewalls and application-level sanitization of all user-supplied URLs and resource identifiers. The implementation of strict allowlists for external service integrations and network access controls can help limit the potential impact of such vulnerabilities. Additionally, organizations should conduct thorough security assessments of their GitLab configurations and review all external service integrations to ensure that no unnecessary access has been granted to internal systems. This vulnerability aligns with CWE-918, which describes server-side request forgery vulnerabilities, and represents a common attack pattern categorized under the ATT&CK framework as T1071.004 for application layer protocol: DNS and T1046 for network service scanning, highlighting the reconnaissance and lateral movement capabilities that such vulnerabilities enable in operational security contexts.