CVE-2026-90493: Tonec Internet Download Manager Kernel Driver idmwfp.sys access control

A vulnerability was detected in Tonec Internet Download Manager up to 6.42 Build 63 on Windows. The impacted element is an unknown function of the file idmwfp.sys of the component Kernel Driver. The manipulation results in improper access controls. Attacking locally is a requirement. Internet Download Manager for Windows up to and including 6.42 Build 63 installs idmwfp.sys, a Windows kernel driver that exposes the \.\IDMWFP device interface to authenticated local users. The device object is created with an access control descriptor equivalent to D:P(A;;GA;;;AU), granting Authenticated Users generic access to the driver. The driver's IOCTL 0x12C028 handler accepts registry-operation subcommands 0x0C through 0x0F and processes caller-controlled registry paths and values. These handlers do not authenticate the caller, do not enforce the caller's registry permissions, and do not restrict operations to IDM-owned registry namespaces. A low-privileged local authenticated user can therefore read, create, modify, and delete arbitrary registry values under HKLM and HKU through the kernel driver. This includes registry configuration consumed by privileged Windows services and drivers and enables Local Privilege Escalation, high-privilege persistence, unauthorized system configuration disclosure or modification, and compromise of system confidentiality, integrity, and availability. Exploitation requires local access, low privileges, and no user interaction. A public proof of concept is available. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.