The source code, part of which was released in April, comes from VMware's ESX hypervisor VMware warned on Sunday that more of its source code for its ESX hypervisor technology could become public after another batch of code was released by a hacker. The source code dates from 2004 and is related to other code released in April, wrote Iain Mulholland, VMware’s director of platform security. He did not indicate what risk the current release poses to customers.“It is possible that more related files will be posted in the future,” Mulholland wrote. He recommended that VMware customers apply the most current product updates and patches while also review their “security hardening guidelines.”VMware’s ESX hypervisor is virtualization software that sits on top of a server’s hardware, enabling multiple guest operating systems to run. A hacker nicknamed “Stun” posted a link on Twitter to a torrent leading to the file, which had also been posted elsewhere.In April, VMware said the source code leak did not necessarily pose an increased risk to customers. But the leak did show how companies face increasing difficulty in protecting some of their most valuable intellectual property. At that time, the source code leak was accompanied by internal VMware emails on Pastebin from “Hardcore Charlie,” a hacker who indicated the material came from China National Electronics Import and Export (CEIEC), an engineering and electronics company that also works with China’s military. The code was part of thousands of documents that Hardcore Charlie claimed to have obtained from the company’s servers.It’s unclear if Hardcore Charlie had a hand in the latest release. He hasn’t posted on Twitter since July 6.Send news tips and comments to jeremy_kirk@idg.com. Follow me on Twitter: @jeremy_kirk Related content feature Top cybersecurity M&A deals for 2023 Fears of recession, rising interest rates, mass tech layoffs, and conservative spending trends are likely to make dealmakers cautious, but an ever-increasing need to defend against bigger and faster attacks will likely keep M&A activity steady in By CSO Staff Sep 22, 2023 24 mins Mergers and Acquisitions Mergers and Acquisitions Mergers and Acquisitions brandpost Unmasking ransomware threat clusters: Why it matters to defenders Similar patterns of behavior among ransomware treat groups can help security teams better understand and prepare for attacks By Joan Goodchild Sep 21, 2023 3 mins Cybercrime news analysis China’s offensive cyber operations support “soft power” agenda in Africa Researchers track Chinese cyber espionage intrusions targeting African industrial sectors. By Michael Hill Sep 21, 2023 5 mins Advanced Persistent Threats Cyberattacks Critical Infrastructure brandpost Proactive OT security requires visibility + prevention You cannot protect your operation by simply watching and waiting. It is essential to have a defense-in-depth approach. By Austen Byers Sep 21, 2023 4 mins Security Podcasts Videos Resources Events SUBSCRIBE TO OUR NEWSLETTER From our editors straight to your inbox Get started by entering your email address below. Please enter a valid email address Subscribe