A vulnerability identified in the Trellix HX Agent driver file fekern.sys allowed a threat actor with local user access the ability to gain elevated system privileges. Utilization of a Bring Your Own Vulnerable Driver (BYOVD) was leveraged to gain access to the critical Windows process memory lsass.exe (Local Security Authority Subsystem Service). The fekern.sys; a driver file associated with Trellix HX Agent (used in all existing HX Agent versions). The vulnerable driver installed in a product or a system running fully functional HX Agent is, itself, not exploitable as the product’s tamper protection restricts the ability to communicate with the driver to only the agent’s processes.
Published: 2026-02-24
Updated: 2026-02-24
Base Score: 7.2
Vector: CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C
Severity: High
Base Score: 7.8
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity: High
Base Score: 7.1
Vector: CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: High