CVE Catalog

CVE-2026-20293

HighCVSS 7.1
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.18%

8th percentile - higher than 8% of all known CVEs

Summary

A vulnerability in the UEFI Shell implementation of Cisco UCS Servers could allow an authenticated attacker with user/admin role or an unauthenticated attacker with physical access to bypass UEFI Secure Boot and execute unauthorized software. This is due to memory write commands available in the UEFI Shell while Secure Boot is enabled, allowing manipulation of preboot environment and execution of unauthorized code.

Risk Assessment

An attacker with physical access or a user account could take control of the boot process, potentially installing malware and compromising system integrity.

Recommendation

Apply Cisco UCS updates and restrict physical access to devices and user account access.

Related vulnerabilities

Original NVD description (English source)

A vulnerability in the Unified Extensible Firmware Interface (UEFI) Shell implementation of Cisco UCS Servers and UCS-based appliances could allow an authenticated attacker with valid credentials for a user account with the role of user or admin or an unauthenticated attacker with physical access to an affected device to bypass UEFI Secure Boot validation checks and execute unauthorized software. This vulnerability is due to the availability of memory write commands in the UEFI Shell while UEFI Secure Boot is enabled on a device. An attacker could exploit this vulnerability by selecting the UEFI Shell boot option at boot time and using available shell commands to modify UEFI memory variables. A successful exploit could allow the attacker to manipulate the preboot environment, overwrite UEFI Secure Boot-related memory values, and execute unauthorized software on the affected device.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS