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CVE-2026-20293

high

A vulnerability in the Unified Extensible Firmware Interface (UEFI) Shell implementation of Cisco UCS Servers and UCS-based appliances could allow an authentic…

Vendor / product: Cisco — enterprise nfv infrastructure software

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.

CVSS
7.1
7.1 (CVSS v3.1)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Severity source: NVD CVSS v3.1 (psirt@cisco.com)
Timeline (UTC)
Published: 2026-09-08 17:17
Modified: 2026-10-26 20:22
NVD status: Analyzed
Last synced 2 days ago
Verified against the source API 2026-10-27 06:51 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

cisco / enterprise_nfv_infrastructure_software 3.3.1, 3.4.1, 3.5.1, 3.5.2, 3.6.1, 3.6.2
cisco / unified_computing_system 4.0\(1a\), 4.0\(1b\), 4.0\(1c\), 4.0\(1d\), 4.0\(2a\), 4.0\(2b\)
cisco / unified_computing_system_e-series_software 4.11.1, 4.12.1, 4.12.2, 4.15.2, 4.15.3, 4.15.4

Weakness classification (CWE)

CWE-749

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ucs-uefi-sb-bypass-eb6xC5GW
Patch / mitigation: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ucs-uefi-sb-bypass-eb6xC5GW

References

Data sources

NVD CVE API 2.0 — fetched 2026-10-27 06:51 UTC · record ↗

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