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In an effort to keep CISA.gov current, the archive contains outdated information that may not reflect current policy or programs.Urgent: Protect Against Active Exploitation of ProxyShell Vulnerabilities
Last Revised
Malicious cyber actors are actively exploiting the following ProxyShell vulnerabilities: CVE-2021-34473, CVE-2021-34523, and CVE-2021-31207. An attacker exploiting these vulnerabilities could execute arbitrary code on a vulnerable machine. CISA strongly urges organizations to identify vulnerable systems on their networks and immediately apply Microsoft's Security Update from May 2021—which remediates all three ProxyShell vulnerabilities—to protect against these attacks.
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