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CVE-2025-4421 is an out-of-bounds write vulnerability in Lenovo-specific firmware code affecting systems that use Insyde BIOS firmware. Available reporting places the flaw in the EfiSmiServices SMM module, specifically involving gEfiSmmCpuProtocol, and characterizes it as an SMM memory corruption issue. The vulnerability is classified as CWE-787 and has been assigned CVSS v3.1 8.2 (AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H). Publicly available information does not currently disclose the exact vulnerable function, code path, or affected firmware version range, but the issue is described as occurring in privileged firmware execution context where improper bounds handling can corrupt SMM memory.
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No public exploit code observed for this vulnerability.
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An SMM memory corruption vulnerability in Lenovo-developed code within EfiSmiServices involving gEfiSmmCpuProtocol, caused by an out-of-bounds write.
An out-of-bounds write vulnerability in Insyde BIOS firmware used by Lenovo systems that could enable local privilege escalation or arbitrary code execution at the firmware level, with potential for persistent firmware implants.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.