CVE-2020-12654: 
Linux Kernel vulnerability analysis and mitigation

A vulnerability was discovered in Linux kernel before 5.5.4 where mwifiex_ret_wmm_get_status() in drivers/net/wireless/marvell/mwifiex/wmm.c allows a remote AP to trigger a heap-based buffer overflow because of an incorrect memcpy operation (CVE-2020-12654). The vulnerability was discovered and reported by Qing Xu and was fixed in kernel version 5.5.4 (Kernel Changelog, Kernel Commit).

The vulnerability exists in the mwifiex_ret_wmm_get_status() function which calls memcpy() without properly validating the destination buffer size. Since the source data comes from a remote access point containing WMM (WiFi Multimedia) elements, a malicious AP could send crafted WMM parameters to trigger a heap buffer overflow. The vulnerability has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (NVD).

A malicious access point could exploit this vulnerability to cause a denial of service (system crash or memory corruption) or potentially execute arbitrary code on vulnerable systems connecting to the malicious AP (Ubuntu Security, Debian Security).

The vulnerability can be exploited remotely by a malicious access point without requiring any user interaction or special privileges. The attack requires physical proximity to the target system since it needs to be within WiFi range (OSS Security).

The vulnerability was fixed in Linux kernel version 5.5.4 by adding proper length validation before calling memcpy(). The fix was backported to various stable kernel branches. Major Linux distributions like Ubuntu and Debian have released security updates to address this vulnerability (Ubuntu USN-4392-1, Debian DSA-4698-1). Users should update their systems to patched kernel versions.