CVE-2026-79655 in Red Hat
Summary
by MITRE • 08/25/2026
A flaw was found in sos clean, a utility within the sos package. This vulnerability allows a local attacker to perform arbitrary file creation or overwrite. By crafting a malicious tar archive, an attacker can exploit a path traversal issue during tar extraction, where symlink and hardlink targets are not properly validated. This enables the attacker to write files to arbitrary locations on the system with the privileges of the sos clean process, which often runs as root.
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Analysis
by VulDB Data Team • 08/25/2026
The vulnerability identified in the sos package specifically affects the sos clean utility, presenting a critical security risk due to its typical execution context. The sos tool is widely deployed in Linux environments for collecting diagnostic and debug information from systems under investigation or troubleshooting scenarios. Because this process often requires elevated privileges to access system logs, kernel dumps, and other sensitive data structures, it frequently operates with root-level permissions. This privilege level amplifies the severity of any flaw within the utility, as successful exploitation grants an attacker control equivalent to that of the superuser account on the target system.
The core technical flaw resides in how sos clean handles archive extraction during its cleanup or processing phases. The vulnerability is classified as a path traversal issue, formally recognized under CWE-22: Improper Limitation of a Pathname to a Restricted Directory. When the utility processes tar archives, it fails to adequately validate symlink and hardlink targets before extracting them. In standard Unix-like operating systems, symbolic links allow files or directories to point to other locations in the file system hierarchy. If an archive contains symlinks pointing outside the intended extraction directory, such as towards /etc/passwd or critical binary paths, a naive extractor will follow these links and write data to the target location rather than within the sandboxed temporary directory designed for sos operations.
An attacker with local access can exploit this flaw by crafting a malicious tar archive that contains carefully constructed symlinks or hardlinks targeting arbitrary files on the host system. When the victim, typically an administrator or automated process running sos clean as root, processes this crafted archive, the utility extracts the contents without verifying the final destination of linked targets. This lack of validation allows the attacker to overwrite existing files with arbitrary content or create new files in sensitive directories. The operational impact is severe, potentially leading to full system compromise through techniques such as replacing critical binaries, modifying configuration files like sshd_config to allow passwordless root login, or planting persistent backdoors within system startup scripts.
From a threat intelligence perspective, this vulnerability aligns with ATT&CK technique T1059: Command and Scripting Interpreter if used in conjunction with other payloads, but more directly relates to file manipulation tactics such as T1564: Hidden Files and Directories or T1222: File and Directory Permissions Modification. The ability to write arbitrary files is a foundational step for many post-exploitation activities, including privilege escalation via SUID bit modification or hijacking of system services.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Administrators should immediately update the sos package to a version that includes patches addressing this path traversal flaw. Until an official patch is available, users can mitigate risk by avoiding the processing of untrusted tar archives with sos clean or by running the utility in a restricted environment such as a container or sandbox where file system access is limited. Furthermore, implementing strict input validation within custom wrappers around sos operations to verify that all extracted paths remain within expected directories can provide an additional layer of defense against similar path traversal vulnerabilities in other utilities. Regular auditing of installed packages and adherence to the principle of least privilege by restricting root execution contexts wherever possible are essential practices for maintaining system integrity.