CVE-2020-36233: 
Bitbucket vulnerability analysis and mitigation

The Microsoft Windows Installer for Atlassian Bitbucket Server and Data Center contains a privilege escalation vulnerability (CVE-2020-36233) that affects versions before 6.10.9, 7.x before 7.6.4, and versions from 7.7.0 before 7.10.1. The vulnerability was discovered and reported by Will Dormann of the CERT/CC, with the public disclosure occurring on February 18, 2021 (CERT Advisory).

The vulnerability stems from weak permissions set on the default installation directory (e.g., C:\Atlassian\Bitbucket). The security issue is characterized by incorrect default permissions (CWE-276) and has received a CVSS v3.1 Base Score of 7.8 (HIGH) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

By default, unprivileged users can create files in the Bitbucket installation directory structure. This weakness allows local attackers to escalate privileges to SYSTEM level on affected Windows systems with the vulnerable Bitbucket software installed (CERT Advisory).

The vulnerability requires local access to the system. An unprivileged user can exploit this vulnerability by placing a specially-crafted DLL file in the Bitbucket installation directory, enabling arbitrary code execution with SYSTEM privileges (CERT Advisory).

The vulnerability has been addressed in Bitbucket versions 7.10.1, 7.6.4, and 6.10.9. Users are advised to upgrade to these fixed versions to remediate the security issue (Atlassian Advisory).