Log4Shell is a critical security vulnerability found in the popular logging library called Log4j, which is widely used in many Java applications. Discovered in December 2021, this vulnerability allows attackers to execute arbitrary code on affected systems by sending specially crafted log messages. The impact of Log4Shell is significant, as it can lead to unauthorized access, data breaches, and system compromise. Organizations using Log4j were urged to update to patched versions to mitigate the risks associated with this vulnerability, highlighting the importance of maintaining software security.