CVE-1999-0138 in Linux
Summary
by MITRE
The suidperl and sperl program do not give up root privileges when changing UIDs back to the original users, allowing root access.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 04/16/2026
The vulnerability described in CVE-1999-0138 affects the suidperl and sperl programs which are designed to execute perl scripts with elevated privileges. These programs implement the set-user-ID (suid) mechanism to temporarily elevate privileges during script execution, but contain a critical flaw in their privilege management implementation. The vulnerability resides in the programs' failure to properly relinquish root privileges after completing the necessary administrative operations, leaving the process running with elevated privileges even when it should have reverted to the original user's permissions.
This flaw represents a classic privilege escalation vulnerability that directly violates the principle of least privilege and can be categorized under CWE-276, which addresses improper privilege management. The technical implementation error occurs when the programs execute the setuid system call to switch to root privileges for script execution, but fail to properly drop these privileges when returning to the original user context. This creates a persistent security risk where any code executed through these programs continues to run with root privileges, potentially allowing attackers to perform administrative actions that should be restricted to authorized users only.
The operational impact of this vulnerability is significant as it provides a direct path for privilege escalation attacks. An attacker who can influence the execution of perl scripts through these programs can potentially gain root access to the system, enabling them to modify system files, install malicious software, create new user accounts, or access sensitive data. The vulnerability affects systems where these programs are installed and used, particularly those running older versions of perl or unix-like operating systems that have not been updated with proper security patches. This issue can be exploited in scenarios where users have the ability to execute perl scripts through these setuid programs, making it particularly dangerous in multi-user environments or systems with web interfaces that process user input through perl scripts.
Security mitigations for this vulnerability should focus on immediate remediation through patching or updating the affected perl installations to versions that properly implement privilege management. Organizations should also consider removing or disabling the suidperl and sperl programs if they are not essential for system operations, as these programs represent a high-risk attack surface. System administrators should implement proper access controls and monitoring to detect unauthorized execution of these programs, while also reviewing other setuid programs on the system for similar privilege management flaws. The vulnerability demonstrates the critical importance of proper privilege handling in system programs and aligns with ATT&CK technique T1068, which addresses privilege escalation through the exploitation of system vulnerabilities, and T1548.001, which covers privilege escalation through the abuse of setuid and setgid programs. Additionally, this vulnerability underscores the need for comprehensive security testing of setuid programs and adherence to secure coding practices that prevent privilege escalation vectors in system-level software components.