A critical vulnerability has been identified in the interprocess communication (IPC) channel of the Secure Firewall Posture module within Cisco Secure Client. This flaw permits an authenticated, local attacker to escalate privileges on affected devices. The vulnerability stems from inadequate validation of user-supplied input. Attackers can exploit this by sending specially crafted IPC messages to a local socket. Successful exploitation allows for limited file write operations using SYSTEM or root privileges. While the vulnerability affects Windows, macOS, and Linux, it poses a greater risk on macOS and Linux. On these operating systems, attackers can achieve full root privileges. Due to this potential for full root compromise, Cisco has assigned a High Security Impact Rating despite the initial score suggesting Medium. Cisco has released software updates to address this vulnerability. Currently, no workarounds are available. This advisory details a serious security concern that requires immediate attention from users. The vulnerability is tracked under CVE-2026-76462.