A critical vulnerability in OpenSSH, identified as CVE-2024-6387 and named 'regreSSHion,' has been discovered. This flaw allows unauthenticated remote code execution (RCE) on glibc-based Linux systems, potentially compromising millions of servers. The vulnerability affects OpenSSH versions from 8.5p1 to 9.7p1 and earlier than 4.4p1. Researchers from Qualys have identified over 14 million potentially vulnerable OpenSSH server instances exposed to the internet, with around 700,000 feasibly exploitable. The flaw is due to a signal handler race condition in sshd, and exploitation can lead to remote root shell access within 6 to 8 hours, enabling full system compromise. Security experts are urging immediate application of the latest patches to mitigate the risk.