CVE-2016-10044 in Linux
Summary
by MITRE • 01/25/2023
The aio_mount function in fs/aio.c in the Linux kernel before 4.7.7 does not properly restrict execute access, which makes it easier for local users to bypass intended SELinux W^X policy restrictions, and consequently gain privileges, via an io_setup system call.
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Analysis
by VulDB Data Team • 01/18/2026
The vulnerability identified as CVE-2016-10044 represents a critical flaw in the Linux kernel's asynchronous I/O implementation that undermines mandatory access control mechanisms. This issue affects kernel versions prior to 4.7.7 and specifically targets the aio_mount function within the fs/aio.c file. The flaw enables local attackers to circumvent SELinux's W^X (Write XOR Execute) policy enforcement, which is designed to prevent memory regions from simultaneously possessing write and execute permissions. The vulnerability arises from insufficient validation of execute access restrictions during the io_setup system call execution, creating an avenue for privilege escalation attacks.
The technical root cause of this vulnerability stems from improper access control enforcement within the kernel's asynchronous I/O subsystem. When the aio_mount function processes mounting operations for asynchronous I/O contexts, it fails to adequately verify that execute permissions are properly restricted for memory mappings. This oversight allows malicious code to manipulate memory regions in ways that violate the fundamental W^X principle that separates data execution from data modification. The io_setup system call serves as the attack vector through which local users can exploit this weakness to bypass security boundaries established by SELinux policies. This flaw demonstrates a classic case of insufficient input validation and access control enforcement in kernel space operations.
The operational impact of CVE-2016-10044 is severe for systems running affected kernel versions, as it provides a direct pathway for local privilege escalation. Attackers can leverage this vulnerability to execute arbitrary code with elevated privileges, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it operates at the kernel level, where successful exploitation can bypass all user-space security measures. Systems utilizing SELinux with W^X policies are especially at risk, as the flaw specifically targets and undermines these security mechanisms. The local nature of the attack means that any user with access to the system can potentially exploit this vulnerability, making it a significant concern for multi-user environments and server systems.
Mitigation strategies for this vulnerability primarily involve applying the kernel patch released with version 4.7.7, which addresses the improper access control in the aio_mount function. Organizations should prioritize kernel updates and ensure all systems are running patched versions to eliminate this attack vector. Additionally, system administrators can implement additional security measures such as disabling unnecessary asynchronous I/O functionality, monitoring for suspicious io_setup system call usage, and maintaining comprehensive audit logs to detect potential exploitation attempts. The vulnerability aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1068, involving exploit for privilege escalation through kernel vulnerabilities. Security teams should also consider implementing runtime protection mechanisms that monitor for anomalous memory access patterns that could indicate exploitation attempts.