CVE-2023-34634: 
Greenshot vulnerability analysis and mitigation

Greenshot version 1.2.10 and below contains an insecure deserialization vulnerability (CVE-2023-34634) that allows arbitrary code execution when opening a maliciously crafted .greenshot file. The vulnerability was disclosed in August 2023 (NVD, CVE).

The vulnerability stems from insecure deserialization of .NET content when a .greenshot file is opened. On a default installation, the .greenshot file extension is associated with the program, meaning that double-clicking a malicious .greenshot file can trigger code execution. The vulnerability has a CVSS v3.1 base score of 7.8 (High) with vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, indicating local attack vector, low attack complexity, no privileges required, and user interaction required (NVD, FortiGuard).

Successful exploitation of this vulnerability can result in arbitrary code execution on the target system, potentially under the security context of SYSTEM. This gives attackers complete control over the affected system, allowing them to execute malicious code with high privileges (FortiGuard).

The vulnerability has been patched in newer versions of Greenshot. Users should upgrade to the latest version available. A fix was implemented through a commit that improves the backwards compatibility for .greenshot files (GitHub).