CVE-2019-5461 in Community Edition
Summary
by MITRE
An input validation problem was discovered in the GitHub service integration which could result in an attacker being able to make arbitrary POST requests in a GitLab instance's internal network. This vulnerability was addressed in 12.1.2, 12.0.4, and 11.11.6.
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Analysis
by VulDB Data Team • 12/18/2023
The vulnerability identified as CVE-2019-5461 represents a critical input validation flaw within GitLab's GitHub service integration component that enables remote attackers to exploit a path traversal or request manipulation mechanism. This issue specifically affects the way GitLab handles external service integration requests, creating a potential attack vector that allows malicious actors to bypass normal access controls and make unauthorized POST requests to internal network resources. The flaw exists in the validation logic that processes incoming data from GitHub service integrations, where insufficient sanitization permits attackers to craft malicious payloads that can be executed within the GitLab instance's internal network boundaries.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the GitLab service integration framework, which operates under CWE-20 standards for input validation failures. When GitLab processes webhook requests or integration data from GitHub services, the system fails to properly validate the source and content of these requests, allowing attackers to inject malicious parameters that can be interpreted as legitimate internal network requests. This represents a classic case of insufficient sanitization and validation of external inputs, creating an attack surface that enables unauthorized access to internal systems that would normally be protected by network segmentation and access controls.
The operational impact of CVE-2019-5461 is significant as it can enable attackers to perform arbitrary actions within the GitLab instance's internal network environment, potentially leading to data exfiltration, system compromise, or further lateral movement attacks. Attackers could leverage this vulnerability to target internal services that are not directly exposed to the internet, effectively bypassing network security controls and gaining access to sensitive internal resources. The vulnerability affects GitLab installations running versions prior to 12.1.2, 12.0.4, and 11.11.6, making it particularly concerning for organizations with outdated systems that have not received the necessary security patches. This issue aligns with ATT&CK technique T1190 for exploitation of remote services and T1071.004 for application layer protocol usage, as it enables attackers to manipulate service integration components to gain unauthorized access.
Organizations should prioritize immediate patching of affected GitLab instances to address this vulnerability, as the remediation involves updating to versions that include proper input validation and sanitization mechanisms. The fix implemented in GitLab 12.1.2, 12.0.4, and 11.11.6 includes enhanced validation of service integration parameters and improved request handling to prevent malicious input from being processed as legitimate internal network requests. Additionally, organizations should implement network segmentation controls and monitoring of service integration activities to detect potential exploitation attempts. Security teams should also consider implementing webhook validation mechanisms and restricting access to internal services through proper firewall rules and access control lists to minimize the potential impact of similar vulnerabilities in the future. The vulnerability demonstrates the importance of validating all external inputs and implementing defense-in-depth strategies to protect against attacks that exploit service integration components.