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CVE-2026-20293

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

HIGH

7.1

CVSS Score

Published: September 8, 2026 at 04:04 PM UTC

Updated: September 11, 2026 at 02:17 PM UTC

3 products affected across 1 vendorUnified Computing SystemEnterprise Nfv InfrastructureUnified Computing System E Series

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Severity

HIGH7.1

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Unified Computing System · Cisco

60%

1.0(0.240001)1.0(0.250003)1.0(1.250002)1.0(1.250032)1.1(0.250016)1.1(0.250022)1.1(0.250025)1.1(0.250026)1.2(0.250011)1.2(0.250013)1.2(0.260005)2.0(1.250096)2.0(1.250127)2.0(2.260062)2.0(2.260101)3.1(1d)3.1(2b)3.1(2c)3.1(2d)3.1(2e)3.1(2g)3.1(2i)3.1(3a)3.1(3b)3.1(3c)3.1(3d)3.1(3g)3.1(3h)3.1(3i)3.1(3j)3.1(3k)4.0(1.240)4.0(1.260003)4.0(1.260004)4.0(1a)4.0(1b)4.0(1c)4.0(1d)4.0(1e)4.0(1g)4.0(1h)4.0(2a)4.0(2b)4.0(2c)4.0(2d)4.0(2e)4.0(2f)4.0(2g)4.0(2h)4.0(2i)4.0(2k)4.0(2l)4.0(2m)4.0(2n)4.0(2o)4.0(2p)4.0(2q)4.0(2r)4.0(4a)4.0(4b)4.0(4c)4.0(4d)4.0(4e)4.0(4f)4.0(4g)4.0(4h)4.0(4i)4.0(4j)4.0(4k)4.0(4l)4.0(4m)4.0(4n)4.0(4o)4.1(1a)4.1(1b)4.1(1c)4.1(1d)4.1(1e)4.1(1f)4.1(1g)4.1(1h)4.1(2a)4.1(2b)4.1(2c)4.1(2d)4.1(2e)4.1(2f)4.1(2g)4.1(2h)4.1(2j)4.1(2k)4.1(2l)4.1(2m)4.1(3a)4.1(3b)4.1(3c)4.1(3d)4.1(3e)4.1(3f)4.1(3g)4.1(3h)4.1(3i)4.1(3j)4.1(3k)4.1(3l)4.1(3m)4.1(3n)4.1(4a)4.2(1a)4.2(1b)4.2(1c)4.2(1d)4.2(1e)4.2(1f)4.2(1g)4.2(1i)4.2(1j)4.2(1k)4.2(1l)4.2(1m)4.2(1n)4.2(2a)4.2(2c)4.2(2d)4.2(2e)4.2(2f)4.2(2g)4.2(3b)4.2(3d)4.2(3e)4.2(3g)4.2(3h)4.2(3i)4.2(3j)4.2(3k)4.2(3l)4.2(3m)4.2(3n)4.2(3o)4.2(3p)4.2(3q)4.2(3r)4.3(1.230097)4.3(1.230124)4.3(1.230138)4.3(2.230207)4.3(2.230270)4.3(2.240002)4.3(2.240009)4.3(2.240037)4.3(2.240053)4.3(2.240077)4.3(2.240090)4.3(2.240107)4.3(2.250016)4.3(2.250021)4.3(2.250022)4.3(2.250037)4.3(2.250045)4.3(2.250063)4.3(2.260007)4.3(2b)4.3(2c)4.3(2e)4.3(2f)4.3(3.240022)4.3(3.240041)4.3(3.240043)4.3(3a)4.3(3c)4.3(4.240142)4.3(4.240152)4.3(4.241014)4.3(4.241063)4.3(4.242028)4.3(4.242038)4.3(4.242066)4.3(4.252001)4.3(4.252002)4.3(4a)4.3(4b)4.3(4c)4.3(4d)4.3(4e)4.3(4f)4.3(5.240021)4.3(5.250001)4.3(5.250030)4.3(5.250033)4.3(5.250043)4.3(5.250045)4.3(5a)4.3(5c)4.3(5d)4.3(5e)4.3(6.250039)4.3(6.250040)4.3(6.250044)4.3(6.250053)4.3(6.250060)4.3(6.250101)4.3(6.250117)4.3(6.260003)4.3(6.260017)4.3(6.260033)4.3(6a)4.3(6b)4.3(6c)4.3(6d)4.3(6e)4.3(6f)4.3(6g)6.0(1.250127)6.0(1.250130)6.0(1.250131)6.0(1.250174)6.0(1.250192)6.0(1.250194)6.0(1.251006)6.0(1.251030)6.0(1.260001)6.0(1b)6.0(1c)6.0(1d)6.0(1e)6.0(1f)6.0(1h)6.0(2.260026)6.0(2.260034)6.0(2.260042)6.0(2.260044)6.0(2.260069)6.0(2b)6.0(2c)

Unified Computing System E Series · Cisco

60%

4.11.1 4.12.1 4.12.2 4.15.2 4.15.3 4.15.4

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (1)

Source: cverecord

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

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.1HIGHcisco

Attack Vector: LOCAL
Complexity: LOW
Privileges: LOW
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: NONE

Vector?

Quick Info

StatusAWAITING ANALYSIS

CWE

CWE-749

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