以下是从该网页截图中获取到的关于漏洞的关键信息，使用简洁的Markdown格式呈现： --- USN-3900-1: GD Vulnerabilities Overview Published Date: 28 February 2019 Overview: Several security issues were fixed in GD. Releases 18.10 18.04 LTS 16.04 LTS 14.04 LTS Packages - GD Graphics Library Details Vulnerability Description: GD incorrectly handled memory when processing certain images. A remote attacker could use this issue with a specially crafted image file to cause GD to crash, resulting in a denial of service, or potentially executing arbitrary code. Update Instructions A standard system update will make all the necessary changes. Update your system to the following package versions: References CVE-2019-6978 CVE-2019-6977 --- 以上信息总结了该漏洞的关键内容，包括漏洞描述、受影响的Ubuntu版本、补丁安装指南以及相关CVE标识。