CISA Warns of Linux Kernel Improper Ownership Management Vulnerability Exploited in Attacks
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CISA has added a critical Linux kernel vulnerability to its Known Exploited Vulnerabilities (KEV) catalog, warning that CVE-2023-0386 is being actively exploited in real-world attacks.\u00a0<\/p>\n
This improper ownership management flaw in the Linux kernel\u2019s OverlayFS subsystem allows local attackers to escalate privileges through unauthorized access to setuid files with capabilities, posing significant risks to Linux-based systems<\/a> across enterprise environments.<\/p>\n The vulnerability, officially designated as CVE-2023-0386, resides within the Linux kernel\u2019s OverlayFS subsystem, a union filesystem that allows one filesystem to be overlaid on top of another.\u00a0<\/p>\n The flaw stems from improper ownership management during file operations between different mount points with varying security contexts.\u00a0<\/p>\n Specifically, the vulnerability occurs when a user copies a capable file from a nosuid mount into another mount, triggering a uid mapping bug that bypasses normal privilege restrictions.<\/p>\n The technical root cause relates to CWE-282 (Improper Ownership Management), where the kernel fails to properly validate and enforce ownership permissions during file copy operations across filesystem boundaries<\/a>.\u00a0<\/p>\n When exploiting this vulnerability, attackers can manipulate the setuid mechanism, which normally allows programs to run with elevated privileges of the file owner rather than the user executing the program.\u00a0<\/p>\n The OverlayFS implementation incorrectly handles capability inheritance during these cross-mount operations, enabling unauthorized privilege escalation.<\/p>\n Local attackers can exploit CVE-2023-0386<\/a> to escalate their privileges from standard user accounts to administrative or root-level access on affected Linux systems.\u00a0<\/p>\n The vulnerability affects systems running vulnerable versions of the Linux kernel with OverlayFS enabled, which is common in containerized environments and modern Linux distributions.<\/p>\n The privilege escalation occurs through the manipulation of file capabilities during copy operations between mount points with different nosuid settings.\u00a0<\/p>\n Attackers can craft malicious capable files and leverage the uid mapping flaw to execute them with elevated privileges despite security restrictions.\u00a0<\/p>\n This type of vulnerability is especially dangerous in multi-tenant environments, containerized infrastructure, and systems where the principle of least privilege is critical for maintaining security boundaries.<\/p>\nOverlayFS Vulnerability \u2013 CVE-2023-0386<\/strong><\/h2>\n