CVE-2013-0296 in pigz
Summary
by MITRE
Race condition in pigz before 2.2.5 uses permissions derived from the umask when compressing a file before setting that file's permissions to match those of the original file, which might allow local users to bypass intended access permissions while compression is occurring.
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Analysis
by VulDB Data Team • 05/12/2026
The vulnerability identified as CVE-2013-0296 represents a significant race condition flaw in the pigz compression utility version 2.2.4 and earlier. This issue specifically affects the file permission handling mechanism during compression operations, creating a window where security controls can be circumvented. The pigz utility, which is a parallel implementation of gzip designed for improved performance through multiple threads, exhibits this weakness when processing files with restricted access permissions. The race condition occurs during the file compression process where the utility first creates temporary compressed files using permissions derived from the system umask setting, before subsequently adjusting those permissions to match the original file's access controls. This temporal gap between initial permission assignment and final permission synchronization creates an exploitable scenario for local attackers.
The technical flaw stems from improper synchronization of file permission operations within the compression workflow. When pigz processes a file, it initially determines the target file permissions based on the current umask value, which typically restricts access to prevent unauthorized viewing or modification. However, during the compression phase, the utility creates intermediate compressed files with these umask-derived permissions rather than maintaining the original file's restrictive access controls. The vulnerability manifests when an attacker can manipulate the timing or access the compressed file during this transitional period, potentially gaining access to data that should remain restricted. This flaw is categorized under CWE-367, which specifically addresses Time-of-Check to Time-of-Use (TOCTOU) vulnerabilities, where the security state changes between the time of verification and the time of use, allowing for privilege escalation or unauthorized access.
The operational impact of CVE-2013-0296 extends beyond simple permission bypass scenarios, creating potential for broader security compromise within systems where pigz is actively used for file compression. Local users with access to the system can exploit this vulnerability to read files that should be restricted, potentially accessing sensitive data or system information that would normally be protected by file access controls. The risk is particularly pronounced in multi-user environments where different users may have varying permission levels and where temporary files created during compression operations could be accessed by unauthorized parties. This vulnerability directly impacts the principle of least privilege and can undermine the security posture of systems relying on pigz for data compression, especially in environments where file confidentiality is paramount. The attack vector requires local system access and is typically not exploitable over network boundaries, but it represents a serious local privilege escalation risk when combined with other system weaknesses.
Mitigation strategies for CVE-2013-0296 focus primarily on upgrading to pigz version 2.2.5 or later, which contains the necessary patches to address the race condition. System administrators should prioritize patching affected installations, particularly in environments where security is a critical concern. Additional protective measures include implementing strict file permission controls and monitoring for unauthorized access attempts during compression operations. The vulnerability demonstrates the importance of proper synchronization in security-critical operations and highlights the need for careful attention to file permission handling in multi-threaded applications. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically focusing on the use of race conditions to bypass access controls. Regular security audits and vulnerability assessments should include checks for outdated compression utilities, as this vulnerability represents a common oversight in system security maintenance.