A security feature bypass vulnerability exists in Microsoft Edge as a result of how memory is accessed in code compiled by the Edge Just-In-Time (JIT) compiler that allows Arbitrary Code Guard (ACG) to be bypassed. By itself, this ACG bypass vulnerability does not allow arbitrary code execution. However, an attacker could use the ACG bypass vulnerability in conjunction with another vulnerability, such as a remote code execution vulnerability, to run arbitrary code on a target system.To exploit the ACG bypass vulnerability, a user must be logged on and running an affected version of Microsoft Edge. The user would then need to browse to a malicious website.The security update addresses the ACG bypass vulnerability by helping to ensure that Microsoft Edge properly handles accessing memory in code compiled by the Edge JIT compiler.