CVE-1999-1210 in Unix
Summary
by MITRE
xterm in Digital UNIX 4.0B *with* patch kit 5 allows local users to overwrite arbitrary files via a symlink attack on a core dump file, which is created when xterm is called with a DISPLAY environmental variable set to a display that xterm cannot access.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability described in CVE-1999-1210 represents a significant security flaw in the xterm terminal emulator implementation on Digital UNIX systems, specifically affecting version 4.0B with patch kit 5. This issue stems from improper handling of core dump files during xterm execution when the DISPLAY environment variable points to an inaccessible display. The vulnerability creates a symlink attack vector that enables local users to overwrite arbitrary files on the system, fundamentally compromising file system integrity and potentially leading to privilege escalation or data corruption.
The technical flaw manifests when xterm processes a DISPLAY variable that references a non-accessible display, causing the application to generate a core dump file. Under normal circumstances, core dumps are created in predictable locations with specific permissions, but the vulnerability allows malicious users to manipulate this process through symbolic link attacks. When xterm creates the core dump file, it does so without proper validation of the target file system path, enabling an attacker to establish a symlink pointing to a critical system file or user file. This weakness directly maps to CWE-59, which describes improper link resolution without limiting the scope of the link, and CWE-22, which covers improper limitation of a pathname to a restricted directory.
The operational impact of this vulnerability extends beyond simple file overwriting, as it provides attackers with a mechanism to manipulate the system's file structure in ways that could compromise system stability and security. Local users with minimal privileges can exploit this flaw to overwrite critical system files, configuration files, or even user data, potentially leading to system instability, privilege escalation, or information disclosure. The attack requires only local access and knowledge of the xterm execution pattern, making it particularly dangerous in multi-user environments where local privilege escalation can lead to broader system compromise.
Mitigation strategies for this vulnerability should focus on implementing proper file system access controls and ensuring that core dump generation does not create predictable file paths that can be manipulated through symbolic links. System administrators should disable core dump generation for xterm when running in environments where symlink attacks are possible, or implement proper file system permissions that prevent attackers from creating malicious symbolic links. Additionally, patching the system with the appropriate Digital UNIX security updates would address the root cause of this vulnerability. The remediation approach aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where local privilege escalation through file system manipulation would be categorized under privilege escalation tactics. Organizations should also consider implementing monitoring for unusual core dump file creation patterns and ensure that all system components properly validate file system paths before creating or modifying files in sensitive locations.