CVE-2025-4979 in Community Edition
Summary
by MITRE • 05/22/2025
An issue has been discovered in GitLab CE/EE affecting all versions before 17.10.7, 17.11 before 17.11.3, and 18.0 before 18.0.1. An attacker may be able to reveal masked or hidden CI variables (that they did not author) in the WebUI, by simply creating their own variable and observing the HTTP response.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 08/09/2025
This vulnerability in GitLab CE/EE represents a critical information disclosure flaw that undermines the security controls designed to protect sensitive CI/CD variables. The issue affects versions prior to specific patch releases including 17.10.7, 17.11.3, and 18.0.1, indicating a widespread impact across multiple major release lines. The vulnerability stems from insufficient access controls within the web user interface that governs variable visibility and access permissions. Attackers can exploit this weakness by simply creating their own CI variable and then observing the HTTP response to extract information about masked or hidden variables that they did not originally author. This represents a fundamental breakdown in the principle of least privilege and access control enforcement that is critical for maintaining the security posture of continuous integration and deployment pipelines.
The technical implementation of this vulnerability demonstrates a failure in proper input validation and output sanitization within GitLab's web interface components. When users create variables through the web UI, the system should enforce strict authorization checks to prevent unauthorized access to variables owned by other users or projects. However, the flaw allows attackers to bypass these controls through a simple HTTP request manipulation technique. The vulnerability specifically affects the variable masking functionality that is designed to protect sensitive information such as API keys, passwords, and other confidential credentials stored within CI/CD pipelines. This type of vulnerability aligns with CWE-284 Access Control flaws, which specifically address improper access control mechanisms that allow unauthorized access to resources or data.
The operational impact of this vulnerability extends far beyond simple information disclosure, as it directly threatens the integrity and confidentiality of CI/CD environments that are critical to modern software development workflows. Attackers who successfully exploit this vulnerability can gain access to sensitive credentials, API tokens, and other confidential information that may be used to compromise downstream systems, access production environments, or perform further attacks within the organization's infrastructure. The ease of exploitation means that even minimal privileged access or simple user accounts could potentially be leveraged to extract valuable information from CI/CD pipelines. This vulnerability particularly affects organizations that rely heavily on GitLab for their software development lifecycle management, as it undermines the security controls that are expected to protect automated deployment processes and sensitive operational data.
The remediation strategy for this vulnerability involves applying the specific patch releases mentioned in the advisory, which contain fixes for the access control implementation within GitLab's web UI. Organizations should prioritize immediate deployment of these patches across all affected GitLab instances to prevent potential exploitation. Additionally, security teams should conduct comprehensive reviews of their CI/CD pipeline configurations to ensure that no unauthorized access has occurred, particularly focusing on any variables that may have been exposed through this vulnerability. The fix should be validated through security testing to confirm that proper access controls are restored and that the variable masking functionality operates as intended. This vulnerability also highlights the importance of regular security assessments and continuous monitoring of CI/CD environments, as it demonstrates how seemingly minor access control flaws can have significant security implications in automated deployment systems. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and credential access techniques, as it allows attackers to obtain unauthorized access to sensitive information that would normally be protected by access controls. Organizations should also consider implementing additional monitoring and alerting mechanisms to detect suspicious variable creation patterns or unauthorized access attempts that could indicate exploitation of this vulnerability.