CVE-2021-47568: 
Linux Debian vulnerability analysis and mitigation

CVE-2021-47568 is a memory leak vulnerability discovered in the Linux kernel's ksmbd component, specifically in the get_file_stream_info() function. The vulnerability was identified and reported through Coverity Scan, with the fix being implemented in Linux kernel version 5.15.6 (NVD).

The vulnerability is characterized by a memory leak condition in the ksmbd filesystem component's get_file_stream_info() function. It has been assigned a CVSS v3.1 base score of 5.5 (Medium) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. The issue stems from a bug introduced in commit 34061d6b76a4 which dealt with the validation of OutputBufferLength in QUERY_DIR, QUERY_INFO, and IOCTL requests (Kernel Patch).

The vulnerability affects system availability through memory resource exhaustion, as indicated by the CVSS metrics showing High impact on availability (A:H) while having no direct impact on confidentiality or integrity. The local nature of the exploit (AV:L) and the requirement for low privileges (PR:L) somewhat limit its potential impact (NVD).

The vulnerability requires local access to the system with low privileges and no user interaction for exploitation. The attack complexity is rated as low (AC:L), indicating that the vulnerability is relatively straightforward to exploit under the right conditions (NVD).

The vulnerability has been fixed through a patch that properly frees memory in the get_file_stream_info() function when certain buffer length conditions are met. The fix was implemented in Linux kernel version 5.15.6 and later versions. Users should upgrade to a patched version of the kernel to mitigate this vulnerability (Kernel Patch).