CVE-2023-52755 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix slab out of bounds write in smb_inherit_dacl()
slab out-of-bounds write is caused by that offsets is bigger than pntsd allocation size. This patch add the check to validate 3 offsets using allocation size.
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Analysis
by VulDB Data Team • 08/07/2026
The vulnerability identified as CVE-2023-52755 represents a critical slab out-of-bounds write condition within the Linux kernel's ksmbd implementation, specifically affecting the smb_inherit_dacl() function. This issue resides in the kernel-based SMB daemon that provides SMB/CIFS file sharing capabilities on Linux systems. The flaw manifests when processing access control list (ACL) inheritance operations, where the kernel fails to properly validate array bounds during memory allocation and manipulation processes. The vulnerability is particularly concerning as it operates within the kernel space, potentially allowing for privilege escalation or system compromise when exploited by malicious actors.
The technical root cause of this vulnerability stems from inadequate bounds checking in the memory management operations of the ksmbd subsystem. When the smb_inherit_dacl() function processes security descriptor data structures, it calculates offsets that should correspond to the allocated memory size of the pntsd structure. However, the patch addresses a scenario where these calculated offsets exceed the actual allocated memory boundaries, creating a slab out-of-bounds write condition. This condition occurs because three specific offsets are validated against the allocation size without proper boundary checks, allowing for writes beyond the intended memory allocation. The vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, though in this kernel context it manifests as a slab memory corruption issue.
The operational impact of CVE-2023-52755 extends beyond simple memory corruption, as it can potentially enable attackers to execute arbitrary code with kernel privileges when exploited. Systems running affected versions of the Linux kernel with ksmbd enabled are at risk, particularly those serving SMB/CIFS shares to untrusted networks or users. The vulnerability's exploitation could lead to complete system compromise, data exfiltration, or denial of service conditions. Attackers could leverage this flaw to gain elevated privileges, modify system files, or establish persistent backdoors within the kernel space. The vulnerability's presence in the kernel-based SMB implementation makes it particularly dangerous for enterprise environments that rely on file sharing services, as it could be exploited through network-based attacks targeting SMB protocols.
Mitigation strategies for CVE-2023-52755 focus primarily on applying the vendor-provided patch that introduces proper bounds validation for the three offsets in the smb_inherit_dacl() function. Organizations should prioritize updating their kernel versions to include the fix, particularly in environments where ksmbd is actively used for SMB file sharing services. System administrators should also implement network segmentation to limit access to SMB services and disable unnecessary SMB shares. Monitoring for suspicious network traffic patterns related to SMB protocol usage can help detect potential exploitation attempts. The fix aligns with ATT&CK technique T1059.001 for command and scripting interpreter, as the vulnerability could enable attackers to execute malicious code with kernel privileges, and T1566.001 for spearphishing attachments, since exploitation might occur through network-based attack vectors targeting SMB services. Additional defensive measures include implementing kernel module signing requirements and maintaining up-to-date security patches across all kernel components to prevent similar memory corruption vulnerabilities from being exploited in the future.