Palo Alto Networks Warns of Active Exploitation of GlobalProtect VPN Flaw Affecting Corporate Networks
Palo Alto Networks has issued a warning regarding the active exploitation of a vulnerability in its PAN-OS GlobalProtect VPN software, identified as CVE-2026-0257. This flaw allows attackers to bypass authentication and establish unauthorized VPN connections, posing a significant threat to corporate networks. Initially rated as a Medium severity issue, the flaw's severity was upgraded to High after reports of active exploitation emerged. The vulnerability requires specific configurations, such as enabled authentication override cookies and a particular certificate setup. Rapid7, a cybersecurity firm, observed exploitation attempts beginning on May 17, 2026, with attackers using forged authentication cookies to gain access. The flaw has been added to the CISA Known Exploited Vulnerability catalog, prompting federal agencies to address the issue by June 1, 2026.