CVE-2025-22043 in Linux
Summary
by MITRE • 04/16/2025
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: add bounds check for durable handle context
Add missing bounds check for durable handle context.
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Analysis
by VulDB Data Team • 02/15/2026
The vulnerability identified as CVE-2025-22043 resides within the Linux kernel's ksmbd subsystem, which provides SMB/CIFS file sharing capabilities for Linux systems. This subsystem enables Linux servers to communicate with Windows clients using the SMB protocol, making it a critical component for enterprise file sharing environments. The ksmbd implementation has been integrated into the mainline kernel to provide native SMB support without requiring external modules, though it has historically required careful security auditing due to the complex nature of network file sharing protocols.
This particular vulnerability represents a missing bounds check within the durable handle context handling mechanism of the ksmbd subsystem. Durable handles are a critical SMB feature that allows clients to maintain persistent connections to file resources across network interruptions and server reboots. When a client establishes a durable handle, the server must maintain state information about this context to ensure seamless operation when the connection is restored. The absence of proper bounds checking in this context creates a potential avenue for memory corruption or arbitrary code execution.
The technical flaw manifests when the ksmbd subsystem processes durable handle requests without validating the size or range of data structures used to maintain handle context information. This missing validation can lead to buffer overflows or out-of-bounds memory access when processing specially crafted SMB requests from malicious clients. The vulnerability specifically affects the handling of durable handle contexts during SMB protocol negotiations and connection management phases, where insufficient input validation allows attackers to manipulate memory layout and potentially execute arbitrary code with kernel privileges.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it represents a potential path to privilege escalation within systems running the affected kernel versions. Attackers exploiting this vulnerability could gain root-level access to systems hosting SMB services, potentially compromising entire network infrastructures. The vulnerability is particularly concerning in enterprise environments where Linux servers act as SMB file shares for Windows clients, as these systems often contain sensitive corporate data and serve as critical infrastructure components. The attack surface is broad since any system running the affected kernel with ksmbd enabled and configured to accept SMB connections could be vulnerable.
Mitigation strategies for CVE-2025-22043 should prioritize applying the latest kernel updates that contain the patched implementation of bounds checking for durable handle contexts. System administrators should also implement network segmentation and access controls to limit exposure of SMB services to trusted networks only. Additional defensive measures include monitoring SMB traffic for anomalous patterns and implementing intrusion detection systems that can identify potential exploitation attempts. The vulnerability aligns with CWE-129, which addresses insufficient bounds checking, and may map to ATT&CK techniques involving privilege escalation and persistence through kernel-level exploits. Organizations should conduct thorough vulnerability assessments of their SMB infrastructure and ensure all systems are updated to patched kernel versions to prevent potential exploitation.