CVE-2021-33391: 
CBL Mariner vulnerability analysis and mitigation

A heap use-after-free vulnerability was discovered in HTACG HTML Tidy version 5.7.28, identified as CVE-2021-33391. The vulnerability exists in the CleanNode() function within the gdoc.c file, which can be triggered when using the -g option (NVD).

The vulnerability is classified with a CVSS v3.1 Base Score of 9.8 (CRITICAL) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. The issue specifically manifests as a heap use-after-free condition in the CleanNode() function when processing HTML data with the -g option (NVD).

If exploited, this vulnerability could allow an attacker to execute arbitrary code on the affected system. The critical CVSS score indicates that successful exploitation could lead to complete system compromise with high impacts on confidentiality, integrity, and availability (NVD).

Multiple Linux distributions have released patches to address this vulnerability. Ubuntu has provided security updates for versions 20.04 LTS, 22.04 LTS, 23.04, and 23.10. Users are advised to update their systems to the patched versions (Ubuntu Security).