CVE-2023-3863: 
Linux Kernel vulnerability analysis and mitigation

A use-after-free vulnerability (CVE-2023-3863) was discovered in the nfcllcpfindlocal function in net/nfc/llcpcore.c in the Linux kernel's NFC implementation. The vulnerability was reported on July 24, 2023, affecting Linux kernel versions prior to 6.5. This flaw impacts systems with NFC capabilities and allows a local user with special privileges to potentially exploit kernel information leak issues (NVD).

The vulnerability stems from improper handling of references in the NFC subsystem's LLCP (Logical Link Control Protocol) implementation. The issue occurs when the nfcllcpfind_local() function fails to properly manage references when accessing local objects from the linked list. This can lead to a race condition where the reference can be dropped and the local object freed before proper reference counting is established (GitHub Commit). The vulnerability has been assigned a CVSS v3.1 base score of 4.1 (MEDIUM) with the vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N (NVD).

When successfully exploited, this vulnerability can lead to kernel information leaks, potentially exposing sensitive system information. Additionally, it may result in system instability or denial of service conditions through kernel crashes (Ubuntu Security, NetApp Advisory).

The vulnerability has been fixed in Linux kernel version 6.5-rc1 through a patch that implements proper reference counting in the nfcllcpfind_local() function. The fix includes re-implementation of the function to properly handle references and the addition of necessary error handling. Major Linux distributions have released security updates to address this vulnerability (Debian Security Advisory, Ubuntu Security).