CVE-2018-8822 in Linux
Summary
by MITRE
Incorrect buffer length handling in the ncp_read_kernel function in fs/ncpfs/ncplib_kernel.c in the Linux kernel through 4.15.11, and in drivers/staging/ncpfs/ncplib_kernel.c in the Linux kernel 4.16-rc through 4.16-rc6, could be exploited by malicious NCPFS servers to crash the kernel or execute code.
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Analysis
by VulDB Data Team • 09/14/2025
The vulnerability identified as CVE-2018-8822 represents a critical buffer handling flaw within the Linux kernel's NCPFS (Novell Core Protocol File System) implementation. This issue affects multiple kernel versions including those through 4.15.11 and the 4.16-rc release cycle, demonstrating the widespread nature of the flaw across different kernel branches. The vulnerability resides in the ncp_read_kernel function which is responsible for reading data from NCPFS servers, making it a fundamental component in network file system operations.
The technical root cause of this vulnerability stems from improper buffer length validation within the ncp_read_kernel function located in fs/ncpfs/ncplib_kernel.c and drivers/staging/ncpfs/ncplib_kernel.c. When malicious NCPFS servers attempt to communicate with vulnerable kernel instances, they can craft specially formatted data packets that exploit the inadequate buffer size checks. This flaw allows attackers to manipulate the buffer boundaries and potentially trigger memory corruption issues. The vulnerability is classified as a buffer overflow condition under CWE-121, which represents a common class of memory safety issues where insufficient bounds checking permits data to be written beyond allocated memory regions.
The operational impact of this vulnerability is severe and multifaceted, encompassing both denial of service and remote code execution capabilities. Malicious NCPFS servers can leverage this flaw to crash the target kernel through controlled memory corruption, resulting in system instability and service disruption. More critically, the vulnerability enables remote code execution, allowing attackers to potentially gain unauthorized control over affected systems. This represents a significant risk for networked environments where NCPFS clients may encounter untrusted network servers, as the exploitation can occur without requiring local privileges or user interaction. The vulnerability affects systems that utilize NCPFS client functionality, particularly those in enterprise environments where Novell NetWare file services might be accessed.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059.007 for command and control through remote execution, and T1499.004 for network denial of service attacks. The attack surface extends beyond simple kernel crashes to include potential privilege escalation scenarios where attackers could leverage the remote code execution capability to establish persistent access. Mitigation strategies should prioritize immediate patching of affected kernel versions to address the buffer handling inconsistencies. Additionally, network segmentation and access controls should be implemented to limit exposure to untrusted NCPFS servers. System administrators should consider disabling NCPFS client support when not actively required, and implement monitoring for unusual network traffic patterns that might indicate exploitation attempts. The vulnerability highlights the importance of thorough input validation in kernel space code and underscores the need for comprehensive security reviews of legacy filesystem implementations that may not receive regular security updates.