CVE-2022-4376 in GitLab
Summary
by MITRE • 05/04/2023
An issue has been discovered in GitLab affecting all versions before 15.9.6, all versions starting from 15.10 before 15.10.5, all versions starting from 15.11 before 15.11.1. Under certain conditions, an attacker may be able to map a private email of a GitLab user to their GitLab account on an instance.
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Analysis
by VulDB Data Team • 05/27/2023
This vulnerability represents a significant privacy and security concern within GitLab's user identification mechanisms, specifically targeting the correlation between email addresses and user accounts. The flaw exists in GitLab instances where user email addresses are not properly anonymized or protected during certain operational conditions, creating a potential avenue for attackers to discover private email addresses associated with specific user accounts. This issue affects multiple version ranges including all versions before 15.9.6, versions from 15.10 before 15.10.5, and versions from 15.11 before 15.11.1, indicating a widespread impact across the GitLab platform's user base.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization within GitLab's user account and email handling systems. When users interact with certain GitLab features or when specific API endpoints are accessed, the system may inadvertently expose private email address information through response data, logs, or error messages. This occurs under specific operational conditions where the application fails to properly mask or filter email addresses that should remain private, allowing an attacker to correlate publicly accessible information with private email addresses. The vulnerability aligns with CWE-200, which addresses improper exposure of sensitive information, and represents a form of user identification correlation that violates privacy principles. Attackers can exploit this weakness by crafting specific requests or monitoring system responses to map private email addresses to corresponding GitLab user accounts.
The operational impact of this vulnerability extends beyond simple privacy concerns, potentially enabling more sophisticated attack vectors such as social engineering campaigns, targeted phishing attacks, or account takeover attempts. When private email addresses are exposed, attackers can leverage this information for credential stuffing attacks against other services where users may have reused passwords, or conduct targeted spear-phishing operations. The vulnerability undermines the trust model that GitLab users expect when interacting with their platform, as it reveals personal information that should remain confidential. This exposure creates a risk of cascading security issues where a single compromised email address can lead to further account compromises across interconnected services. The vulnerability also violates the principle of least privilege and data minimization, as it exposes more information than necessary for legitimate system operations.
Organizations affected by this vulnerability should immediately upgrade to the patched versions of GitLab, specifically versions 15.9.6, 15.10.5, and 15.11.1, to resolve the issue. The patch addresses the underlying data exposure mechanisms by implementing proper email address sanitization and ensuring that private email information is not leaked through system responses. System administrators should also conduct thorough audits of their GitLab instance configurations to identify any custom settings or third-party integrations that might inadvertently expose user email information. Additional mitigations include implementing network-level controls to monitor for suspicious API access patterns, configuring proper logging and alerting for unusual email address correlation attempts, and reviewing user access controls to ensure that only authorized personnel can access potentially sensitive user information. From a threat modeling perspective, this vulnerability aligns with attack techniques described in the ATT&CK framework under T1566 for credential harvesting and T1592 for reconnaissance, making it a critical concern for security operations teams.