CVE-1999-1496 in sudo
Summary
by MITRE
Sudo 1.5 in Debian Linux 2.1 and Red Hat 6.0 allows local users to determine the existence of arbitrary files by attempting to execute the target filename as a program, which generates a different error message when the file does not exist.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability described in CVE-1999-1496 represents a classic information disclosure flaw in the sudo command utility that affected versions 1.5 in Debian Linux 2.1 and Red Hat 6.0 operating systems. This issue stems from the improper handling of file existence checks within the sudo execution process, creating a scenario where local attackers can infer the presence or absence of specific files on the system through carefully crafted error message analysis. The vulnerability operates at the application level and specifically targets the sudo command's file validation mechanisms, which are critical components for privilege escalation and system security.
The technical root cause of this vulnerability lies in the inconsistent error messaging behavior of sudo when processing file execution requests. When a user attempts to execute a command through sudo, the utility performs internal file validation checks that produce different error messages depending on whether the target file exists. This differential behavior creates an information leakage channel that allows attackers to determine file existence without direct access to the files themselves. The flaw is classified under CWE-200, which deals with information exposure, and represents a form of side-channel information disclosure that can be exploited by local users with minimal privileges. The vulnerability operates through the command execution pathway and can be categorized under ATT&CK technique T1068, which involves exploiting legitimate credentials to execute commands with elevated privileges.
The operational impact of this vulnerability is significant for system security, as it enables local attackers to perform reconnaissance activities that could lead to more sophisticated attacks. An attacker could systematically test for the existence of sensitive files such as configuration files, backup copies, or system binaries by observing the error messages returned by sudo. This information gathering capability could be leveraged to identify potential targets for privilege escalation or to map out system structures that might be useful for further exploitation. The vulnerability affects all users who have the ability to execute sudo commands, making it particularly dangerous in multi-user environments where different users have varying levels of sudo access. The issue represents a fundamental flaw in the sudo command's security model, as it violates the principle of least privilege by leaking information about file system structure.
Mitigation strategies for this vulnerability should focus on immediate patching and system updates to address the specific error handling behavior in sudo versions 1.5. Organizations should ensure that all systems running affected sudo versions are updated to patched releases that properly handle file existence checks without exposing information through error messages. System administrators should also implement additional monitoring to detect unusual sudo usage patterns that might indicate reconnaissance activities. The vulnerability highlights the importance of proper error handling in security-critical applications and demonstrates the need for comprehensive testing of security mechanisms to prevent information leakage. Access control measures should be reviewed to ensure that only authorized users have sudo privileges, and logging should be enhanced to capture sudo command execution attempts for audit purposes. This vulnerability serves as a reminder of how seemingly minor implementation flaws in security utilities can create significant information disclosure risks that compromise system integrity and confidentiality.