01 Record

CVE-2020-27339

In the kernel in Insyde InsydeH2O 5.x, certain SMM drivers did not correctly validate the CommBuffer and CommBufferSize parameters, allowing callers to corrupt either the firmware or the OS memory.

UnratedPUBLISHEDCNA: mitre

CNA base scoreUnratedNo CNA CVSS vector

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02 Description

In the kernel in Insyde InsydeH2O 5.x, certain SMM drivers did not correctly validate the CommBuffer and CommBufferSize parameters, allowing callers to corrupt either the firmware or the OS memory.

03 Exploitation and scoring

Exploitation: Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
SSVC decision: Not assessed by CISA
EPSS probability: 0.32% probability of exploitation activity in the next 30 days.
EPSS percentile: Ranks above 24.3% of scored records. A rank, not a probability.
NVD base score: 6.7 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD analysis status: Modified. NVD last modified this record on 2026-08-11.
Red Hat severity: No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.