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Advisory severityHigh7.1Cisco PoC reported

High [CVE-2026-20293] Cisco UCS and UCS-Based Appliances UEFI Shell Secure Boot Bypass Vulnerability

This high-severity Cisco advisory covers CVE-2026-20293 affecting Unified Computing System E-Series Software (UCSE), Unified Computing System (Managed), Unified Computing System (Standalone).

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

cisco-sa-ucs-uefi-sb-bypass-eb6xC5GW Source published Source updated

VulniPulse record published Record updated

CVE-2026-20293
Affected products & platforms
CiscoUnclassified
Open source advisory

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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.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

Affected products named by the advisory: Unified Computing System E-Series Software (UCSE); Unified Computing System (Managed); Unified Computing System (Standalone); Enterprise NFV Infrastructure Software.

Affected versions
  • Scope: This vulnerability affects the following Cisco products if they have UEFI Secure Boot enabled and are running a vulnerable BIOS version:
  • Earlier than 4.12 — Migrate to a fixed release
  • Release 4.12 (first fixed: 4.12.9 (Jan 2027))
  • 4.13 — Migrate to a fixed release
  • 4.14 — Migrate to a fixed release
  • Release 4.15 (first fixed: 4.15.7 (Nov 2026))
  • Earlier than 4.3 — Migrate to a fixed release
  • Release 4.3 (first fixed: 4.3(6k))
  • Release 6.0 (first fixed: 6.0(2e))
  • Release 4.3 (first fixed: 4.3(6h))
  • Release 6.0 (first fixed: 6.0(2d))
  • Earlier than 5.4 — Migrate to a fixed release
  • Release 5.4 (first fixed: Release no. TBD (Nov 2026))
  • Release 6.0 (first fixed: 6.0(1.260031))
  • Release 5.4 (first fixed: 5.4(0.260050))
  • Release 6.0 (first fixed: 6.0(2.260143))
  • Release 5.4 (first fixed: 5.4(0.260042))
  • Release 2.0 (first fixed: Release no. TBD (Oct 2026))
  • Release 4.0 (first fixed: 4.0(2.260004))
  • Release 1.2 and earlier (first fixed: Release no. TBD (Oct 2026))

Official advisory · high-confidence parse· fetched 16 days ago·verify at source

Fixed versions
  • 4.12.9 (Jan 2027)
  • 4.15.7 (Nov 2026)
  • 4.3(6k)
  • 6.0(2e)
  • 4.3(6h)
  • 6.0(2d)
  • Release no. TBD (Nov 2026)
  • 6.0(1.260031)
  • 5.4(0.260050)
  • 6.0(2.260143)
  • 5.4(0.260042)
  • Release no. TBD (Oct 2026)
  • 4.0(2.260004)

Official advisory · high-confidence parse· fetched 16 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Upgrade to the first fixed release for your train per the Fixed Releases table in this advisory.
  • Earlier than 4.12: migrate to a fixed release.
  • Release 4.12: upgrade to 4.12.9 (Jan 2027).
  • Release 4.13: migrate to a fixed release.
  • Release 4.14: migrate to a fixed release.
  • Release 4.15: upgrade to 4.15.7 (Nov 2026).
  • Earlier than 4.3: migrate to a fixed release.
  • Release 4.3: upgrade to 4.3(6k).
  • Release 6.0: upgrade to 6.0(2e).
Workaround status
  • There are no workarounds that address this vulnerability.

Official advisory · high-confidence parse· fetched 16 days ago·verify at source

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