Cisco Secure Client EUVD-2026-107381

Exploitation requires the Cisco Secure Client Secure Firewall Posture module to be installed and running, and the attacker must already hold an authenticated local (unprivileged) account on the affected endpoint - there is no network or remote vector (AV:L). The specific prerequisite is local access to the Posture module's IPC local socket, to which the attacker sends crafted IPC messages. Limiting factors: no remote exploitation, prior local authentication required (PR:L), and direct impact on Windows is limited to constrained SYSTEM-privileged file writes - only on macOS and Linux can this be escalated to full root, so those platforms carry the higher real-world risk.

This is a genuine but second-tier priority: a local privilege-escalation flaw, not a remotely exploitable one. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N, base 5.5 Medium) confirms the attacker must already have authenticated local access to the device and that the only direct impact is to integrity (file write), with no confidentiality or availability impact scored. Cisco deliberately raised its Security Impact Rating to High above the Medium base score, because on macOS and Linux the limited SYSTEM/root file write can be leveraged into full root compromise - a meaningful gap between the numeric score and real-world worst case that defenders should weigh. No EPSS score, CISA KEV listing, or public POC was provided in the intelligence, so there is no public exploit identified at time of analysis and no evidence of active or widespread exploitation; the local-only vector makes mass automated exploitation unlikely regardless. Net: patch on a normal-to-prioritized cadence (favoring macOS/Linux endpoints where full root is achievable), but this is not an emergency drop-everything issue absent new exploitation signals.

An attacker who already has an unprivileged authenticated session on a host running Cisco Secure Client with the Secure Firewall Posture module sends a series of crafted IPC messages to the module's local socket. Insufficient input validation lets the attacker trigger file write operations executed with SYSTEM (Windows) or root (macOS/Linux) privileges; on macOS and Linux this can be escalated to full root control. No public exploit code was identified in the provided data.