CVE-1999-0413 in IRIX
Summary
by MITRE
A buffer overflow in the SGI X server allows local users to gain root access through the X server font path.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 04/18/2026
The vulnerability described in CVE-1999-0413 represents a critical buffer overflow flaw within the Silicon Graphics Incorporated X server implementation that enables local attackers to escalate privileges to root access. This issue specifically targets the font path handling mechanism of the X Window System server, which is a fundamental component of graphical user interfaces in Unix-like operating systems. The vulnerability arises from insufficient bounds checking when processing font path specifications, creating an exploitable condition that can be leveraged by malicious local users to execute arbitrary code with elevated privileges.
The technical nature of this flaw aligns with CWE-121, which categorizes buffer overflow conditions where insufficient boundary checks allow attackers to overwrite adjacent memory locations. The X server's font path processing routine fails to properly validate input length when handling font path specifications, allowing an attacker to supply overly long font path strings that exceed the allocated buffer space. This overflow can overwrite critical memory segments including return addresses, function pointers, or other control data structures within the server's execution context. The vulnerability specifically affects the X server's handling of font paths through the XFontPath configuration mechanism, which is commonly used to specify directories where font files are stored and accessed by the graphical system.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise. Local users who can execute code on the system can exploit this buffer overflow to gain root access, effectively providing them with unrestricted control over the entire system. The attack vector requires only local system access, making it particularly dangerous as it can be exploited by users who may not have elevated privileges initially. Once exploited, the attacker can modify system files, install malware, create backdoors, or extract sensitive information from the compromised system. This privilege escalation vulnerability undermines the fundamental security model of Unix-like systems where local users should not be able to gain root access through application flaws.
Mitigation strategies for this vulnerability should focus on immediate patching of the affected X server implementations and implementation of additional security controls. System administrators should apply the vendor-provided security patches that address the buffer overflow in font path handling, ensuring that all font path specifications are properly validated for length and content. The recommended approach includes implementing input validation controls that enforce strict bounds checking on all font path parameters, utilizing stack protection mechanisms, and employing address space layout randomization to complicate exploitation attempts. Additionally, system hardening measures such as disabling unnecessary font path configurations, restricting font path access to authorized users only, and implementing monitoring for unusual font path operations should be considered. This vulnerability demonstrates the critical importance of proper input validation in graphical server implementations and aligns with ATT&CK technique T1068 which covers privilege escalation through exploitation of software vulnerabilities. The incident underscores the necessity of comprehensive security testing for graphical subsystems and proper memory management practices in server applications to prevent similar buffer overflow conditions from compromising system integrity.