CVE-2001-1593 in a2ps
Summary
by MITRE
The tempname_ensure function in lib/routines.h in a2ps 4.14 and earlier, as used by the spy_user function and possibly other functions, allows local users to modify arbitrary files via a symlink attack on a temporary file.
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Analysis
by VulDB Data Team • 05/09/2026
The vulnerability identified as CVE-2001-1593 represents a critical security flaw in the a2ps printing utility version 4.14 and earlier, specifically within the tempname_ensure function located in lib/routines.h. This issue manifests as a race condition vulnerability that enables local attackers to manipulate temporary files through symbolic link attacks, potentially leading to arbitrary file modification. The flaw is particularly concerning because it affects the spy_user function and likely other functions within the application that utilize temporary file handling mechanisms, creating a broad attack surface for privilege escalation and data integrity compromise.
The technical implementation of this vulnerability stems from improper temporary file creation practices within the a2ps utility. When the tempname_ensure function generates temporary filenames, it does not adequately validate or secure the temporary file creation process against symbolic link manipulation. Attackers can exploit this by creating a symbolic link with the expected temporary filename in the directory where the temporary file would be created, effectively redirecting file operations to arbitrary locations on the filesystem. This type of vulnerability aligns with CWE-377, which specifically addresses insecure temporary file creation practices, and falls under the broader category of race condition vulnerabilities that are classified as CWE-362 in the CWE database. The vulnerability represents a classic example of a time-of-check to time-of-use (TOCTOU) race condition where the security check occurs before the file operation, allowing attackers to manipulate the file system between these two points.
The operational impact of CVE-2001-1593 extends beyond simple file modification capabilities, as it can enable attackers to escalate privileges and compromise system integrity. When local users exploit this vulnerability, they can potentially overwrite critical system files, inject malicious code into temporary files that will be executed by the application, or manipulate configuration files that the a2ps utility may access. The attack vector is particularly dangerous because it requires minimal privileges and can be executed by any local user who has access to the system. This vulnerability is categorized under the MITRE ATT&CK framework as a privilege escalation technique, specifically falling under the T1068 category for "Exploitation for Privilege Escalation" and potentially T1059 for "Command and Scripting Interpreter" if attackers use the compromised temporary files to execute malicious code. The vulnerability can be leveraged by attackers to establish persistent access or to gain elevated privileges on the system.
Mitigation strategies for CVE-2001-1593 should focus on addressing the core temporal vulnerability in the temporary file creation process. System administrators should immediately upgrade to a2ps version 4.15 or later, where this vulnerability has been patched through improved temporary file handling mechanisms. The patch typically implements proper file descriptor creation with appropriate permissions and ensures that temporary files are created with secure, non-symlinkable names. Additionally, organizations should implement proper file system permissions and access controls to limit the impact of potential exploitation. Security measures should include monitoring for unauthorized symbolic link creation in directories where temporary files are used, and implementing proper privilege separation for applications that handle temporary file operations. The vulnerability highlights the importance of following secure coding practices as outlined in the CERT Secure Coding Standards, specifically addressing the avoidance of race conditions in file operations and the implementation of proper temporary file management techniques. Organizations should also consider implementing intrusion detection systems to monitor for suspicious file system activities that may indicate exploitation attempts.