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Fencer Vulns
high 7.1

CVE-2026-20293 json

Cisco UCS and UCS-Based Appliances UEFI Shell Secure Boot Bypass Vulnerability

published 2026-09-08 2 mo ago modified 2026-10-26 13 d ago also EUVD-2026-72936

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

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.

Patch / fix

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
58 d ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected products

  • Cisco Cisco Enterprise NFV Infrastructure Software
  • Cisco Cisco Unified Computing System (Managed)
  • Cisco Cisco Unified Computing System (Standalone)
  • Cisco Cisco Unified Computing System E-Series Software (UCSE)

Classification

Weakness
  • CWE-749 Exposed Dangerous Method or Function

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.