Microsoft has taken the rare step of releasing fixes outside its usual Patch Tuesday roundup and released an emergency security update to fix two critical issues, including a zero-day vulnerability.
The zero-day lies in the Internet Explorer scripting engine and has been exploited in the wild, while the other bug is for Microsoft Defender.
The IE zero day is what researchers call a remote code execution (RCE) issue.
"The vulnerability could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user," said Microsoft. "An attacker who successfully exploited the vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited the vulnerability could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights."
The Microsoft Defender bug is a denial of service (DoS) vulnerability, which, Microsoft said in a security update: "an attacker could exploit the vulnerability to prevent legitimate accounts from executing legitimate system binaries. To exploit the vulnerability, an attacker would first require execution on the victim system."
Microsoft released security updates for both issues:
