CVE-2024-53217 in Linux
Summary
by MITRE • 12/27/2024
In the Linux kernel, the following vulnerability has been resolved:
NFSD: Prevent NULL dereference in nfsd4_process_cb_update()
@ses is initialized to NULL. If __nfsd4_find_backchannel() finds no available backchannel session, setup_callback_client() will try to dereference @ses and segfault.
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Analysis
by VulDB Data Team • 12/15/2025
The vulnerability CVE-2024-53217 represents a critical null pointer dereference issue within the Linux kernel's Network File System Daemon implementation. This flaw exists in the nfsd4_process_cb_update() function where the session pointer ses is initialized to NULL but fails to properly validate the session existence before attempting to dereference it. The issue occurs during the callback update process in NFSv4 implementations where the system attempts to establish or maintain backchannel communication between the server and client. When the __nfsd4_find_backchannel() function cannot locate an available backchannel session, the setup_callback_client() function proceeds to dereference the uninitialized ses pointer, leading to a kernel panic or system crash.
The technical nature of this vulnerability aligns with CWE-476, which specifically addresses NULL pointer dereference conditions in software implementations. This type of vulnerability represents a classic race condition and improper validation scenario where the kernel fails to properly check for valid session handles before proceeding with operations that assume their existence. The flaw manifests in the NFS daemon's callback processing mechanism where the system assumes that a backchannel session exists when it may not, creating a path for arbitrary code execution or system instability. The vulnerability is particularly dangerous because it operates at the kernel level where such faults can result in complete system compromise or denial of service conditions.
The operational impact of CVE-2024-53217 extends beyond simple system crashes to potentially enable remote attackers to cause denial of service against NFS services or exploit the kernel panic for privilege escalation. When the null pointer dereference occurs during callback processing, it can cause the entire NFS daemon to terminate unexpectedly, disrupting file sharing services and potentially allowing attackers to force system reboots or create persistent denial of service conditions. The vulnerability affects systems running Linux kernels with NFSv4 server implementations, particularly those that rely on callback mechanisms for maintaining session state and coordination between NFS servers and clients. This issue can be particularly severe in enterprise environments where NFS services are critical for data storage and sharing operations, as it can lead to complete service outages and data access disruptions.
Mitigation strategies for CVE-2024-53217 should focus on immediate kernel updates to patched versions that properly validate session existence before dereferencing pointers. System administrators should prioritize applying the relevant kernel security patches that address this specific null pointer dereference condition in the NFS daemon implementation. Additional protective measures include implementing network segmentation to limit exposure of NFS services to untrusted networks, monitoring for unusual NFS daemon behavior or frequent crashes, and establishing robust logging mechanisms to detect potential exploitation attempts. The vulnerability also highlights the importance of proper input validation and defensive programming practices in kernel space code, as recommended by various cybersecurity frameworks including those aligned with the ATT&CK framework's defense evasion and execution tactics. Organizations should also consider implementing intrusion detection systems that can monitor for abnormal NFS service behavior or kernel panic patterns that may indicate exploitation attempts.