Federal agencies are alerting on the active exploitation of a patched Windows SMB vulnerability, CVE-2025-33073. Microsoft issued a fix in June 2025 after researchers publicly disclosed this flaw, which enables attackers to elevate privileges to SYSTEM level on affected Windows and Windows Server systems by exploiting improper access control in the SMB client. The Cybersecurity and Infrastructure Security Agency (CISA) has added the vulnerability to its Known Exploited Vulnerabilities list, reflecting credible evidence of attacks. Systems without SMB signing enforcement are particularly at risk, as attackers can manipulate unsigned SMB messages. Federal agencies have been mandated to patch affected systems by November 10, 2025, while CISA urges all organizations to apply updates promptly to mitigate ongoing threats. Several proof-of-concept exploits have been published by security researchers since June.