CVE-2024-50283 in Linux
Summary
by MITRE • 11/19/2024
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix slab-use-after-free in smb3_preauth_hash_rsp
ksmbd_user_session_put should be called under smb3_preauth_hash_rsp(). It will avoid freeing session before calling smb3_preauth_hash_rsp().
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Analysis
by VulDB Data Team • 07/16/2025
The vulnerability identified as CVE-2024-50283 resides within the Linux kernel's ksmbd implementation, specifically affecting the SMB3 pre-authentication hash response handling mechanism. This issue represents a classic use-after-free condition that can potentially compromise system integrity and availability. The ksmbd subsystem serves as a kernel module that provides SMB/CIFS file sharing capabilities, making it a critical component in enterprise environments where file server functionality is essential. When properly configured, ksmbd enables Linux systems to function as SMB servers, facilitating file sharing between Linux and Windows systems through the SMB protocol.
The technical flaw manifests in the smb3_preauth_hash_rsp function where the ksmbd_user_session_put operation is not properly synchronized with the function execution flow. This improper sequencing creates a scenario where session resources are freed before the smb3_preauth_hash_rsp function completes its execution, leading to a use-after-free condition in the kernel's slab memory allocator. The slab allocator manages memory blocks for frequently allocated objects, and when freed memory is accessed after deallocation, it can result in memory corruption, arbitrary code execution, or system crashes. This vulnerability directly maps to CWE-416, which defines use-after-free conditions as a critical memory safety issue that can be exploited by attackers to gain unauthorized access or cause denial of service.
The operational impact of this vulnerability extends beyond simple system instability, as it can be exploited by remote attackers to execute arbitrary code with kernel privileges. An attacker who successfully exploits this vulnerability could gain complete control over the affected system, potentially leading to data exfiltration, privilege escalation, or the establishment of persistent backdoors. The vulnerability affects systems running Linux kernels with ksmbd functionality enabled, particularly those serving SMB/CIFS shares in enterprise environments. The exploitation potential is heightened because SMB protocols are commonly used in corporate networks, making the attack surface substantial. Organizations that rely on Linux-based file servers for SMB sharing operations are particularly at risk, as this vulnerability could be leveraged to compromise entire network infrastructures.
Mitigation strategies for CVE-2024-50283 should prioritize immediate kernel updates from vendors that include the patched implementation of ksmbd. System administrators must ensure that all affected Linux distributions receive and install the relevant security patches that address the improper session resource management in the smb3_preauth_hash_rsp function. Additionally, network segmentation and access control measures should be implemented to limit exposure of SMB services to trusted networks only, reducing the attack surface. Monitoring for suspicious SMB traffic patterns and implementing intrusion detection systems can help identify potential exploitation attempts. Organizations should also consider disabling SMB services when not required and implementing strict authentication controls to minimize the risk of unauthorized access. The fix implemented in the patched kernel versions ensures proper synchronization between session resource deallocation and function execution, preventing the premature freeing of session objects that could lead to memory corruption. This remediation aligns with the ATT&CK framework's mitigation strategies for kernel-level exploits, emphasizing the importance of maintaining up-to-date system patches and implementing proper memory management practices in kernel modules.