The U.S. Cybersecurity and Infrastructure Security Agency has issued an alert about a zero-day flaw in a widely used enterprise VPN product that is already being exploited. The agency urged organizations to apply security updates without delay and review exposure across remote access systems.

According to the advisory, the vulnerability could allow attackers to compromise protected network access tools that many businesses rely on for remote work and internal operations. CISA did not immediately disclose the full technical details, but the warning signals active risk for organizations that have not yet patched.

Security officials have increasingly warned that VPN products remain attractive targets because they sit at the edge of corporate networks. When attackers exploit these systems, they can gain a foothold inside sensitive environments and move quickly to steal data or disrupt services.

CISA’s notice adds to a growing list of urgent cybersecurity advisories as defenders race to close gaps before more systems are breached. Organizations using the affected software were advised to check vendor guidance, confirm whether they are exposed, and strengthen monitoring for suspicious activity.