Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-20753

Severity CVSS v4.0:
HIGH
Type:
CWE-190 Integer Overflow or Wraparound
Publication date:
12/05/2026
Last modified:
13/05/2026

Description

Integer overflow in the UEFI firmware for the Slim Bootloader may allow an escalation of privilege. System software adversary with a privileged user combined with a low complexity attack may enable local code execution. This result may potentially occur via local access when attack requirements are present without special internal knowledge and requires no user interaction. The potential vulnerability may impact the confidentiality (high), integrity (high) and availability (high) of the vulnerable system, resulting in subsequent system confidentiality (high), integrity (high) and availability (high) impacts.

Impact

Vector 4.0
CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H CVSS v4.0 Severity and Metrics:

Base Score: 8.70 HIGH
Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Attack Vector (AV): Local
Attack Complexity (AC): Low
Attack Requirements (AT): Present
Privileges Required (PR): High
User Interaction (UI): None
Confidentiality (VC): High
Integrity (VI): High
Availability (VA): High
Confidentiality (SC): High
Integrity (SI): High
Availability (SA): High

Base Score 4.0
8.70
Severity 4.0
HIGH

References to Advisories, Solutions, and Tools