CVE-2021-28660: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-28660 is a buffer overflow vulnerability discovered in the Linux kernel through version 5.11.6, specifically in the rtwwxsetscan function within drivers/staging/rtl8188eu/osdep/ioctl_linux.c. The vulnerability allows writing beyond the end of the ->ssid[] array. This vulnerability was disclosed on March 17, 2021, affecting various Linux-based systems and devices using the RTL8188EU wireless driver (NVD).

The vulnerability exists in the rtwwxset_scan function where there was insufficient validation of SSID lengths in scan results. The original code had a check to prevent read overflow but lacked proper validation to prevent writing beyond the end of the ->ssid[] array. The issue has been assigned a CVSS v3.1 base score of 8.8 (HIGH) with the vector CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. The vulnerability is classified as CWE-787 (Out-of-bounds Write) (NVD, Kernel Patch).

When successfully exploited, this vulnerability could lead to denial of service (crash or memory corruption), disclosure of sensitive information, addition or modification of data, or potentially arbitrary code execution on vulnerable systems. The attack requires the attacker to be within WiFi range of the target system (NetApp Advisory, Debian Advisory).

The vulnerability was fixed in Linux kernel version 5.11.7 through a patch that adds proper validation of SSID lengths. The fix involves adding an additional check to ensure that sec_len is less than or equal to 32 before performing the memory copy operation. Various Linux distributions have released security updates to address this vulnerability, including Debian with versions 4.19.181-1~deb9u1 and 4.9.272-1, and Fedora with kernel-tools version 5.11.7-200.fc33 (Kernel Patch, Debian Advisory, Fedora Update).