CVE-2020-11668: 
Linux Kernel vulnerability analysis and mitigation

CVE-2020-11668 affects the Linux kernel before version 5.6.1, specifically in the drivers/media/usb/gspca/xirlink_cit.c (Xirlink camera USB driver) component. The vulnerability was discovered and disclosed on April 9, 2020. The issue involves improper handling of invalid descriptors, also known as CID-a246b4d54770 (NVD, Kernel Changelog).

The vulnerability stems from insufficient validation of USB device descriptors in the Xirlink camera USB driver. The driver fails to verify that it has two alternate settings and at least one endpoint before accessing the second altsetting structure and dereferencing the endpoint arrays. This can lead to NULL-pointer dereferences or memory corruption when a device does not have the expected descriptors. The vulnerability has a CVSS v3.1 Base Score of 7.1 (HIGH) with vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H (NVD).

When successfully exploited, this vulnerability could allow a physically present attacker with a specially constructed USB device to cause a denial-of-service (system crash) or potentially achieve privilege escalation (Ubuntu).

The vulnerability requires local access and a specially crafted USB device to exploit. The attack complexity is considered low, requiring only limited privileges and no user interaction. The vulnerability has been confirmed to be exploitable in real-world scenarios (NVD).

The vulnerability was fixed in Linux kernel version 5.6.1. The fix includes adding proper descriptor sanity checks to verify the presence of two alternate settings and at least one endpoint before accessing the altsetting structure. Various Linux distributions have released security updates to address this vulnerability, including Ubuntu, Debian, and others (Kernel Patch).