Introduction
An attacker with local access to a Lenovo all-in-one desktop can use a firmware flaw to gain deep persistence and bypass security controls at the hardware level. CVE-2025-4423 is one of six high-impact vulnerabilities in Lenovo's System Management Mode (SMM) firmware. It allows memory corruption that can survive an OS reinstall and evade traditional detection.
Two companies are involved.
Lenovo is a major global PC manufacturer. Its product line covers desktops, laptops, and enterprise devices, and its systems are widely deployed in both consumer and business environments. A flaw in Lenovo firmware therefore reaches a large number of machines.
Insyde Software is a major supplier of UEFI firmware to OEMs, Lenovo among them. Flaws in Insyde's codebase have affected multiple vendors, which widens the reach of firmware vulnerabilities like CVE-2025-4423.
Technical Information
CVE-2025-4423 is a buffer overflow vulnerability (CWE-119) in the System Management Mode (SMM) firmware of certain Lenovo all-in-one desktops. SMM routines do not properly restrict operations to the bounds of a memory buffer. Exploitation requires local or physical access to the device. An attacker can supply crafted input that overruns the intended buffer and corrupts SMM memory. From there, the attacker can modify UEFI variables and install persistent malware that runs below the operating system and evades most endpoint security controls.
Binarly researchers identified this vulnerability as part of a cluster of six SMM-related flaws (CVE-2025-4421 to CVE-2025-4426). All six are associated with the Insyde-based firmware that Lenovo uses. Exploitation complexity is high, because the attacker needs detailed knowledge of firmware internals as well as privileged or physical access. No public code snippets or proof of concept are available for this specific CVE.
Affected Systems and Versions
- Products: Lenovo all-in-one desktop models using Insyde-based firmware
- Advisory: LEN-201013
- CVE Range: CVE-2025-4421 through CVE-2025-4426
- Specific models and firmware versions: See Lenovo's official advisory for the complete list of affected products and firmware versions.
Vendor Security History
Lenovo has fixed similar firmware vulnerabilities before, including buffer overflows and SMM issues (e.g., CVE-2025-4657). For CVE-2025-4423, Lenovo coordinated its patch response with Binarly and released advisories and firmware updates promptly. Its reliance on third-party BIOS vendors like Insyde, however, has contributed to recurring vulnerabilities across its product lines. Insyde's firmware has been implicated in multiple cross-vendor security advisories, which points to systemic risk in the firmware supply chain.
