CVE-1999-1461 in IRIX
Summary
by MITRE
inpview in InPerson on IRIX 5.3 through IRIX 6.5.10 trusts the PATH environmental variable to find and execute the ttsession program, which allows local users to obtain root access by modifying the PATH to point to a Trojan horse ttsession program.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability described in CVE-1999-1461 represents a classic privilege escalation flaw affecting the InPerson messaging system on IRIX operating systems. This issue specifically targets the inpview component which is responsible for handling incoming messages and utilizing the ttsession program for session management. The vulnerability stems from a fundamental design flaw where the inpview application fails to properly validate or sanitize the PATH environment variable before executing the ttsession program, creating an exploitable condition that allows local attackers to escalate privileges to root access.
The technical root cause of this vulnerability lies in the insecure execution pattern where the application relies on the default PATH resolution mechanism to locate and execute the ttsession program. When the inpview process executes ttsession, it does not explicitly specify the full path to the program but instead depends on the system PATH variable to locate it. This approach creates a race condition and privilege escalation opportunity because any user with access to the system can manipulate the PATH variable to point to a maliciously crafted version of ttsession located in a directory that appears earlier in the PATH than the legitimate system location. The vulnerability is particularly dangerous because it operates at the system level where the inpview process runs with elevated privileges, making the privilege escalation directly exploitable.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential full system compromise. Attackers can leverage this flaw to gain root access without requiring authentication, effectively bypassing all security controls that depend on proper privilege separation. The vulnerability affects a broad range of IRIX versions from 5.3 through 6.5.10, indicating it was a persistent issue across multiple releases of the operating system. This widespread impact suggests that the underlying flaw was not properly addressed in security patches, leaving numerous systems vulnerable to exploitation. The vulnerability also demonstrates the importance of proper privilege management and secure coding practices in system-level applications.
The exploitation of this vulnerability aligns with several attack patterns documented in the MITRE ATT&CK framework, particularly those related to privilege escalation and credential access. The attack vector represents a form of path manipulation or environment variable manipulation that falls under the category of "Abuse Elevation of Privilege" techniques. From a CWE perspective, this vulnerability corresponds to CWE-426 Untrusted Search Path, which specifically addresses the issue of applications using untrusted input to determine program execution paths without proper validation. The vulnerability also relates to CWE-78 Improper Neutralization of Special Elements used in OS Command Injection, as the PATH manipulation allows for command execution with elevated privileges. Organizations should implement immediate mitigations including proper PATH validation in application code, ensuring that executables are referenced with absolute paths rather than relying on PATH resolution, and conducting comprehensive system audits to identify and patch affected versions of the InPerson system.
This vulnerability highlights critical security principles that remain relevant in modern system design and development practices. The flaw demonstrates the necessity of implementing secure coding standards that prevent the use of untrusted input in critical execution paths, particularly in system-level applications that operate with elevated privileges. Modern security frameworks emphasize the importance of privilege separation and the principle of least privilege, where applications should not be granted unnecessary elevated permissions. The vulnerability also underscores the importance of proper input validation and the need for applications to explicitly verify the integrity of executable paths before execution. Organizations should adopt comprehensive security measures including regular vulnerability assessments, patch management programs, and security configuration reviews to prevent similar issues from occurring in contemporary systems. The persistence of this vulnerability across multiple IRIX versions emphasizes the need for robust security practices throughout the software lifecycle, from initial development through ongoing maintenance and support.