CVE-2021-39919 in Community Edition
Summary
by MITRE • 12/13/2021
In all versions of GitLab CE/EE starting version 14.0 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2, the reset password token and new user email token are accidentally logged which may lead to information disclosure.
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Analysis
by VulDB Data Team • 12/16/2021
This vulnerability affects GitLab Community Edition and Enterprise Edition across multiple version ranges including 14.0 through 14.3.5, 14.4 through 14.4.3, and 14.5 through 14.5.1. The issue stems from improper logging practices where sensitive authentication tokens are inadvertently written to log files during password reset and user registration workflows. This represents a significant information disclosure vulnerability that directly violates security best practices for handling sensitive data. The flaw manifests when the system generates reset password tokens and new user email tokens, which are then logged in plain text format without proper sanitization or obfuscation mechanisms.
The technical implementation of this vulnerability involves the logging subsystem failing to properly filter or mask authentication tokens before writing them to system logs. This occurs during critical authentication flows when users request password resets or when new user accounts are created and verified via email. The tokens generated for these processes typically contain sufficient entropy to allow unauthorized access if captured by an attacker with access to the logging infrastructure. This vulnerability aligns with CWE-209, which addresses the improper handling of sensitive information in error messages and logs, and also corresponds to ATT&CK technique T1565.001 regarding data manipulation through log injection or exposure. The logging mechanism appears to process all parameters passed to the authentication endpoints without distinguishing between regular operational data and sensitive cryptographic tokens.
The operational impact of this vulnerability is substantial as it provides attackers with direct means to compromise user accounts. An attacker who gains access to the GitLab system logs could extract password reset tokens and new user email verification tokens, enabling them to reset passwords for arbitrary user accounts or verify email addresses for malicious purposes. This creates a privilege escalation pathway where unauthorized individuals can gain access to user accounts without needing to know existing credentials. The vulnerability affects all users within the affected GitLab instances, making it particularly dangerous in multi-tenant environments where multiple organizations share the same GitLab installation. The exposure of these tokens could lead to unauthorized code access, data breaches, and potential lateral movement within the organization's infrastructure.
Mitigation strategies for this vulnerability include immediate patching to versions 14.3.6, 14.4.4, or 14.5.2 depending on the affected version range. Organizations should also implement log sanitization procedures that automatically filter out authentication tokens and other sensitive data before logging. This can be achieved through custom logging filters or by modifying the GitLab configuration to disable logging of sensitive parameters. Additionally, organizations should conduct log access reviews to ensure only authorized personnel can view system logs containing sensitive information. The implementation of proper input validation and output sanitization practices should be enforced across all authentication flows. Security monitoring should include log scanning for sensitive data patterns, and regular log audits should be performed to identify any potential exposure of tokens. This vulnerability highlights the importance of following the principle of least privilege in logging and demonstrates how seemingly minor logging oversights can create significant security risks that align with ATT&CK technique T1565.002 for credential access through log file manipulation.