CVE-2021-38091: 
Ffmpeg vulnerability analysis and mitigation

Integer Overflow vulnerability was discovered in the filter16_sobel function within libavfilter/vf_convolution.c of FFmpeg version 4.2.1. This vulnerability was assigned CVE-2021-38091 and was publicly disclosed on September 20, 2021. The vulnerability affects FFmpeg installations and has received a CVSS v3.1 base score of 8.8 (High) (NVD).

The vulnerability is classified as an Integer Overflow or Wraparound (CWE-190) that occurs in the filter16_sobel function of FFmpeg's convolution filter implementation. The issue manifests when processing certain input values, leading to signed integer overflow conditions. The vulnerability received a CVSS v3.1 vector of CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, indicating it can be exploited remotely with low attack complexity but requires user interaction (NVD).

When successfully exploited, this vulnerability can lead to Denial of Service conditions and potentially other unspecified impacts. The high severity ratings for confidentiality, integrity, and availability impacts suggest that successful exploitation could significantly affect system security (NVD).

A fix for this vulnerability has been implemented and committed to the FFmpeg repository. The patch addresses the undefined behavior in the convolution filter implementation. Users are advised to upgrade to patched versions of FFmpeg. Ubuntu has released security updates for affected versions, particularly in Ubuntu 20.04 LTS (focal) with version 7:4.2.7-0ubuntu0.1+esm3 (Ubuntu Security).